Abstract: With the rapid development of China’s economy and the shipping trade ,the operating of ships has seriously polluted China’s ocean environment，but China’s legal system in preventing vesselsource ocean pollutions lags far behind. It has the defects of lack of specific basic law，imperfection of corresponding laws and regulations，failure to distinct different territorial waters effectively，weakness in law enforcement，etc. Drawing lessons from the United States of America，the authors suggest that legal system in preventing vesselsource ocean pollutions should be perfected from the aspects of legislation，perfection of corresponding regulations and compensation fund system，etc.

Key words: ocean environment, vesselsource pollutions, oil spill in free sea, law enforcement on ocean, compensation fund for ship damage