Contrastive argument is an effective argument method, which reveals the differences between two things or viewpoints through comparison, thus making the expounded facts more profound and convincing. This method can be applied to many situations, for example, the comparison between true and false can help to eliminate the false and keep the true, the comparison between good and evil can suppress evil and promote good, and the comparison between right and wrong can set things right. In argumentative writing, comparative argument can make the correct argument more stable, and at the same time, it can make readers understand the author's point of view more clearly. In addition, comparative demonstration can also strengthen the demonstration effect through vertical ratio (the comparison between the previous period in time and the previous period in things) and horizontal ratio (the comparison between similar things). For example, through the comparison of historical figures or events, we can more clearly show the different results brought by different choices, thus supporting the author's point of view.