Abstract: The criminal prosecution of the Environmental Protection Department plays an important role in environmental law enforcement in HongKong. In terms of staffing, the central prosecution unit is responsible for its professionalism and independence and is not subject to the investigation unit; In the process of making a prosecution decision or review, the prosecutor considers and weighs the evidence and the public interest sufficiently to make environmental law enforcement more effective; In the way of law enforcement, fixed penalty is imposed on some minor environmental violations, making environmental law enforcement more flexible. Under the background of deepening ecological system reform, the criminal prosecution of the Environmental Protection Department in HongKong can provide some reference for China's environmental law enforcement system reform, such as improving the independence of environmental law enforcement agencies, broadening the connotation of the proportion principle to achieve reasonable measurement of public interests, innovating environmental law enforcement methods, and achieving flexible law enforcement.