Frazil jams are common ice phenomena in rivers in winter and also threaten the safe operation and limit the water conveyancing efficiency of long-distance canal systems in cold regions. In this paper, based on the canal pool conditions from the Fenzhuanghe sluice to the Beijumahe sluice of the Middle Route of the South-to-North Water Diversion Project, the analytic hierarchy process (AHP) and the fault tree principle (FTP) for frazil jam risk assessment are proposed. The risk factors of frazil jams are then identified based on the AHP. Then the probability and consequence severity of frazil jams induced by each risk factor are scored by experts, and the weights of each risk factor are proposed. Finally, risk level and prevention measures are proposed. The results show that there are 20 risk factors for canal frazil jams and the possibility of risk factors is positively correlated with the consequence severity. As yet, experts have not formed a unified view on the frazil jam mechanism of water diversion projects, and the scoring results are highly dependent on expert positions. This paper recommends the FTP as the frazil jam risk evaluation method, and the corresponding frazil jam level of the project is level III.