Taking the global impact of Japan's nuclear sewage discharge as the starting point, this paper studies the harm caused by Japan's nuclear sewage flowing into the Pacific Ocean, the harm to the world's organisms, the impact on seaside workers, and investigates the harmful phenomenon of nuclear sewage to human beings. This paper is divided into four parts: the first part briefly introduces the harm of nuclear wastewater and how much nuclear wastewater needs to be discharged; the second part describes the source of nuclear wastewater in Japan; the third part summarizes the introduction literature of nuclear wastewater and the existing problems of nuclear wastewater in Japan; and the fourth part gives rise to the selfish thinking that Japan only concerns about its internal affairs. The research content of this paper mainly includes the nuclear sewage discharge incident in Japan, which caused immeasurable and serious consequences. Japan must also face consequences for its actions.