笔者近期在中学发现很多历史教师在讲解日本侵华战争时都少不了讲到当时国共内战为日本侵华提供了机会。诚然,此说并无问题,但不少学生提出了这样一个问题:侵华作为日本既定国策,而20年代的中国正值北洋军阀混战后期,又有北伐战争,为何日本不在20年代发动侵华战争?为此,笔者特写此文来对该问题做一简要分析。主要原因与当时日本的“币原外交”政策有关。1918年 The author recently found out that many history teachers in the course of explaining Japan’s war of aggression against China had invariably mentioned that the civil war between the KMT and the CPC at that time provided an opportunity for Japan’s invasion of China. It is true that there is no problem with this statement, but many students have raised this issue: Invading China as an established national policy of Japan, and in the 1920s, China was in the late period of the Northern warlords and the Northern Expedition. Why did Japan not invade China in the 1920s? For this reason, the author made a brief analysis of the issue in this article. The main reason was related to Japan’s currency diplomacy policy. 1918