本文探討三個時期的天命思想，首先說明三國為何以天命作為其政權的正當性根 源。其次說明在以天命作為政權正當性根源的思想之下，所進行的一系列相關的天命在己， 受命改制及災異的觀念。 三國之所以競相以天命作為其政權正當性的根源，乃是因為自周初即以天命作為政權正當性 的根源，一直到三國時期此種思想仍未改變，人們甚至以此作為選擇某個政權的準則，如張 魯，魯肅等人都是如此。 然而「天無二主，地無二王」，且天命在誰也非空口宣稱即可，因此三國大抵以宣稱自己有 盛德，各種符應並出及讖緯預言等內容來證明天命在己。其中曹魏與孫吳為證明其為應天作 新王，因而又進行正朔，服色等事項的改制。 政權天授，然而天命靡常，所以政權建立之後仍需時時戒慎恐懼，以求長保天命。因此，曹 魏的文帝、明帝，東吳的孫權，對於作為上天之譴告的災異也都特別重視，二國之臣也常借 災異的出現上疏以勸諫國君。 經由上述的說明，我們發現，東漢末年開始，儒學雖然有所衰微，但天命思想卻仍然具有極 大的影響。

　　　　　This article probes into the idea of God's will in the Three Kingdoms. Firstly it states why rulers took God's will as proper root of state power in the Three Kindgoms. Secondly it introduces serial related ideas of God's will on you, received reforming and disaster, under the idea of taking God's will as proper root of state power. The reason why rulers all took God's will as proper root of state power in the Three Kingdoms is that this root has never been changed from the early of the Chou Dynasty till the Three Kingdoms. People even thought it as a principle, such as Change Lu, Lu Su etc. While only one supreme ruler in a country, as there is only one sun in heaven. Furthermore we cannot just call God's will on somebody. So rulers of the Three Kingdoms almost proved God's will on you by declaring their great reputation, various phenomena and unknown prophecy etc. and Cao-Wei and Sun-Wu carried out reforming in the calendars, clothes color etc. for proving that they became kings according to God's will. God awards state power, while God's will is unpredicted. So urlers must act with caution after founding state power for keeping long-term God's will. Therefore Emperor Wen and Emperor Ming of Cao-Wei and Sun-Chuan of Sun-Wu especially emphasized God's warning-disaster, and ministers of these two countries often remonstrated their kings by such disaster. As the above said, we could find that although Confucianism has slacked off gradually from the last year of the Eastern Han Dynasty, the idea of God's will still had great effect.