元朝五次遣使日本，二次东征日本，均遭失败。日本特殊的地理位置和海洋性气候是元朝惨败的客观因素；元朝军队作战部署失当、人民存在厌战心理、元朝对日本东征的非正义性则成为元朝东征日本失败的主观因素 The Yuan Dynasty dispatched Japan five times and the second eastward Japan, all failed. Japan’s special geographical location and maritime climate are the objective factors of the defeat in Yuan Dynasty. The deployment of battles by the army in the Yuan Dynasty is not appropriate and the people are mentally retarded. The unjustness of the Yuan Dynasty toward the Japanese expedition became the subjective factor of the Yuan Dynasty’s defeat in Japan