Abstract: Since the first planting of genetically modified (GM) plants in the United States, in 1996, the global commercial growing area of GM crops has been steadily increasing; in 2010, the total growing area reached 148 million hm². Currently, the main commercial traits are herbicide tolerance (HT) and insect resistance, with HT crops occupying 81% of the total hectares of GM plants. Although use of herbicide-tolerant crops largely extends the herbicide application space, it may pose environmental risks that have been a continual concern and debated worldwide. We examined the literature and here discuss the environmental risks related to herbicide-tolerant GM crops, focusing on gene flow, weediness and effects on biodiversity, as well as corresponding assessment procedures and methods. We summarize the current research progress and the associated risk management strategies to provide the scientific basis for development, risk assessment and management of herbicide-tolerant GM crops in China.