Homare Sawa and Yuki Nagasato both netted to send host China crashing out of the women's Olympic Tournament in Qinhuangdao on Friday.
The game at the Olympic Sports Center Stadium was a meeting between two of Asia's biggest rivals, with a crowd of 28,459 crowd.
Japan scored just 15 minutes into the game, with Sawa heading home an Aya Miyama corner.
China had the majority of possession in the second half but failed to really threaten the Japanese goal. The Japanese extended their lead when Nagasato fired home in the 79th minute.
Norio Sasaki's side now meet the U.S. in a re-match of their Group G game, which they lost 1-0.