Abstract: DongPoWaiJi is the main and better original of SU Shi's letters (from the 175th to the 809th), which was edited in the period between Northern Song(960-1127) and Southern Song(1125-1210) Dynasty, in order to complete the whole works of SU Shi. The rest part of letters (from the 1st to the 174th) came from another bad original of "text-system" in Song Dynasty, which can be represented by DongPo-HanMoChiDu (Edition of FenXinGe Series). Today, researchers always use DongPoXuJi as the only source of SU Shi's letters, which is just the later consequence of the two originals. It is to say, whenever we study SU Shi by his letters, the first-hand texts are not DongPoXuJi but DongPoWaiJi and DongPo-HanMoChiDu.