日主是什麼？怎麼從八字找到自己的日主
作者：Wei Chun Chuang・2026-10-15
讀八字時，第一個要找的字就是「日主」。它是整張命盤的參考點，之後的五行關係與十神都要從它推出來。這篇說明日主是什麼、怎麼找，以及找到之後可以怎麼看。
日主是什麼意思？
八字由年、月、日、時四柱組成，每柱有一個天干和一個地支，共八個字。其中「日柱的天干」就叫日主，也稱日元或日干。傳統上把它看成命盤裡的「我」，其他七個字都是相對於日主來描述的。
怎麼從八字找到自己的日主？
步驟很簡單：
- 取得完整的四柱。四柱需要依曆法換算，現在多由萬年曆或排盤工具計算。
- 找到第三柱，也就是日柱。
- 日柱上面那個字（天干）就是你的日主。
例如某人的日柱是「丙午」，日主就是丙；日柱是「癸卯」，日主就是癸。注意不是年柱的天干，也不是生肖。
十個天干分別屬於哪一行？
日主一定是十天干之一，每個天干都有五行與陰陽：
- 甲（陽木）、乙（陰木）
- 丙（陽火）、丁（陰火）
- 戊（陽土）、己（陰土）
- 庚（陽金）、辛（陰金）
- 壬（陽水）、癸（陰水）
所以「日主丙」也可以說成「陽火日主」。常見的比喻是甲為大樹、乙為花草、丙為太陽、丁為燈燭，這些只是幫助記憶的意象，不同書的說法不完全相同。
日柱是怎麼決定的？
日柱依六十甲子循環，從甲子、乙丑一路排到癸亥，每天往下走一個，六十天一輪，和農曆的月份大小無關。比較需要留意的是出生在深夜接近子時的人：子時跨越晚上十一點到凌晨一點，不同流派對於晚上十一點是否換日有不同做法，因此日柱、日主可能出現差異。出生時間接近這個區段時，最好知道自己用的工具採用哪一種規則。
為什麼讀八字要從日主出發？
因為命盤裡的關係都是「相對於日主」來說的。以五行生剋為基礎，其他天干和日主會形成五種關係：同我、我生、我剋、剋我、生我，再依陰陽異同細分，就是十神。也就是說，不先找到日主，就無法判斷其他字對你扮演什麼角色。
找到日主之後可以先看什麼？
初學者可以先做兩件事：第一，記住自己日主的五行與陰陽；第二，看看命盤上其他七個字各屬哪一行，和日主是相生、相剋還是同類。這就是讀懂一張八字的第一步。
常見問題
- 日主和生肖一樣嗎？
- 不一樣。生肖看的是年柱的地支，日主是日柱的天干，兩者在命盤上的位置不同。
- 同一天出生的人日主都一樣嗎？
- 同一天出生、採用同一套換日規則，日柱就相同，日主也相同。差異主要出現在接近子時、各流派換日規則不同的情況。
- 日主有分強弱嗎？
- 傳統上會看日主在整張命盤中得到多少生扶，這屬於進階主題。初學時先找到日主、認識它的五行與陰陽即可。
想用 App 練習？
想直接在自己的命盤上找日主，時來－八字是一款教你讀八字的 iPhone 課程 App：四柱由 App 計算，前三堂免費課的第三堂就是「找到日主，讀懂第一個關係」；另有每日一題，用當天的天干對照你的日主練習，作答後才展開完整推導。目前已送 App Store 審核，尚未上架。
What is the Day Master? How to find yours in a Bazi chart
作者：Wei Chun Chuang・2026-10-15
When reading a Bazi chart, the first character to find is the Day Master. It is the chart's reference point: the Five Phases relationships and the Ten Gods are all worked out from it. This article explains what it is, how to find it and what to look at next.
日主是什麼意思？
A Bazi chart has four pillars, year, month, day and hour, each with one heavenly stem and one earthly branch, for eight characters in total. The heavenly stem of the day pillar is called the Day Master, also the day stem. Traditionally it represents "me" in the chart, and the other seven characters are described relative to it.
How do you find your Day Master?
步驟很簡單：
- Get your full four pillars. They require a calendar conversion and are usually calculated with a perpetual calendar or a chart tool.
- Find the third pillar, the day pillar.
- The top character of the day pillar, its heavenly stem, is your Day Master.
If someone's day pillar is Bing-Wu, the Day Master is Bing; if it is Gui-Mao, the Day Master is Gui. It is not the year stem, and it is not the zodiac animal.
Which phase does each of the ten stems belong to?
The Day Master is always one of the ten stems, each with a phase and a polarity:
- 甲（陽木）、乙（陰木）
- 丙（陽火）、丁（陰火）
- 戊（陽土）、己（陰土）
- 庚（陽金）、辛（陰金）
- 壬（陽水）、癸（陰水）
So a Bing Day Master can also be called a yang Fire Day Master. Common images compare Jia to a tall tree, Yi to grass and flowers, Bing to the sun and Ding to a candle. These are memory aids, and books differ in the details.
日柱是怎麼決定的？
Day pillars follow the sixty-day cycle from Jia-Zi and Yi-Chou through to Gui-Hai, moving one step each day regardless of the lengths of lunar months. The case to watch is a birth late at night near the Zi hour, which runs from 11 p.m. to 1 a.m. Schools differ on whether the day changes at 11 p.m., so the day pillar and Day Master can differ. If you were born in that window, find out which rule your tool uses.
Why does Bazi reading start from the Day Master?
Because every relationship in the chart is described relative to it. Based on the Five Phases cycles, each other stem relates to the Day Master in one of five ways: same as me, produced by me, controlled by me, controlling me, or producing me. Split by matching or opposite polarity, these become the Ten Gods. Without the Day Master you cannot tell what role any other character plays for you.
What should you look at after finding it?
Beginners can do two things. First, remember your Day Master's phase and polarity. Second, check which phase each of the other seven characters belongs to and whether it produces, controls or matches your Day Master. That is the first step to reading a Bazi chart.
常見問題
- 日主和生肖一樣嗎？
- No. The zodiac animal comes from the year pillar's branch; the Day Master is the day pillar's stem. They sit in different places in the chart.
- Does everyone born on the same day share a Day Master?
- With the same day-change rule, people born on the same day share a day pillar and Day Master. Differences arise near the Zi hour, where schools use different rules.
- Is a Day Master strong or weak?
- Traditionally readers assess how much support the Day Master receives from the rest of the chart. That is an advanced topic; beginners should first find it and learn its phase and polarity.
Practise with an app
To find the Day Master on your own chart, Shilai – Bazi is an iPhone course that teaches you to read Bazi. The app calculates the four pillars, and the third free lesson is "Your Day Master's first relationship". A daily question compares that day's stem with your Day Master, opening the full derivation after you answer. It is currently in App Store review.