Abstract: The base reason why XIANG Yu gave LIU Bang a good dinner in Hongmen Banquet was XIANG didn t know LIU would become the dangerous enemy in the future days which he controlled China.Not only didn t he know it before the banquet,in the banquet,but also he didn t know it after the banquet for fourteen or fifteen months.The thought that XIANG gave LIU a good dinner in Hongmen Banquet were due to XIANG s kindness,LIU s peerage of Wu an Marquis or inactive Guanzhong King,and XIANG couldn t kill LIU were rong.