Sinclair, from Burnaby, B.C., led the Canadian team with three goals at the four-nation competition. She also earned tournament most valuable player honours.
The Canadian captain scored on a penalty kick in the 63rd minute and added the winning goal a minute later. Gu Yasha scored China's lone goal in the 31st minute.
The round-robin finale at the Shenzhen Bao'an Sports Center served as a preview for the opening game of the 2015 women's World Cup. Canada and China will kick off that tournament June 6 at Edmonton's Commonwealth Stadium.
"It's nice to build some momentum with the huge year ahead of us," Sinclair said.
Canada swept its three games in the competition, posting 2-1 victories over South Korea and Mexico over the last week.
"It's just nice to win something," coach John Herdman said. "I think Canada has been at this tournament five times and tried before to win it and this is the first time we've done it. So it's nice to win things and get that winning feeling across the team."
Canada previously played in the tournament in 2004, 2008, 2011 and 2013.