My thesis is to talk about the China-USA trade war. The trade war was started on March 22, 2018. I focus on the reason for the trade war and discuss whether the trade war is reasonable. I used two methods, the spillover effect and event-study to analyze four markets and compared the data in every date of tariffs announcement between China and the U.S. But both countries all suffered massive damage from the trade war. Therefore, I think the trade war is unreasonable.