On October 17，2018，Canada became the second country in the world to legalize cannabis. For more than half a century，domestic political climate，trends of social thoughts，international anti-drug atmosphere，and the neighboring United States have shaped the tone of the debate on cannabis legalization. Since the passing of the Cannabis Act，new changes have taken place in the awareness and acceptance of cannabis among Canadians，while the social consequences of juvenile cannabis use and crimes related to cannabis have also made legalization controversial. Although there may not be fundamental changes in the direction of legalization，political parties，public opinion，and the game between the federal and local governments will continue to improve the details of cannabis legalization policies in future.