Abstract: The study aims to strengthen the understanding of Leptosphaera maculans of rapeseed, improve the prevention and quarantine awareness, control the spread, epidemic and harm of the disease, protect the safe production of rapeseed in China and promote the healthy development of rapeseed industry. By analyzing the distribution, economic harmfulness, invasion possibility and difficulty of prevention and control of L. maculans at home and aboard, and taking into consideration the economic, ecological and social benefits of rapeseed, the authors evaluated the hazard risk of L. maculans with reference to the international pest risk analysis method. The results showed that: the risk value of L. maculans in China was 2.59, belonging to special high risk level. Since the invasion of the pathogen might bring a tremendous threat to the rapeseed production in China, we should take strategies such as import quarantine, inspection of the pathogen and resistance breeding.