In 2020，the outbreak and spread of COVID-19 have strong impact on Japan’s domestic politics，economy，society and diplomacy，with Japan’s mode of epidemic prevention coming with frustration and the Tokyo Olympic Games forced to be postponed. The performance of LDP administration had a strong start but gradually showed weakness. The former prime minister Shinzo Abe had to resign and his successor Suga Yoshihide，faced with difficulties，had to balance his policy between epidemic prevention and economic recovery. In 2020，Japan’s economy has fallen into recession with the -4.8% annual growth rate of GDP. The epidemic has also hit Abe’s “diplomacy overlooking the globe”，with Japan’s strategic activeness declining and relations with neighbouring countries stuck in dilemma. However，Japan has actively carried out “epidemic diplomacy”，promoted progress in bilateral and multilateral cooperation and made new progress in the diplomacy towards Europe and Southeast Asia. Japan also continues to promote cooperation with “middle powers”，focus on efforts to build new “strategic pivots” by deepening Japan-EU relations and introducing the “European factor” into the Asia-Pacific and India-Pacific regions to build a regional strategic balance that is favorable to Japan. With U.S. Democratic candidate Joe Biden won the presidential election，the Japan-U.S. alliance come to be restrengthened. In 2020，Sino-Japanese relations have fluctuated and encountered new problems and challenges. With the spread of COVID-19 in Japan，U.S. passing off the responsibility to China on the origin of COVID-19 and the rising contradiction between China and Japan on East China Sea and Diaoyu Island issues，there has been growing negative statement and action from the side of Japanese government and LDP，and the Suga administration attempts to make use of the “epidemic card” to touch the bottom line of China in Taiwan and Xinjiang issues. Looking into the year 2021，under the impact of variables such as COVID-19，Japan’s domestic politics and China-U.S.-Japan interaction，Sino-Japanese relations will be faced with more uncertainty.