Abstract: In order to delivery water in Long Distance Canal System (LDCS) in winter smoothly, it is necessary to study its operation process. Considering the differences of flow behaviors between LDCS and natural rivers, a juxtaposition floating ice-cover model was developed, which can simulate and describe the floating ice cover formation process and winter operation responses of LDCS, such as changing process of water level, gate opening, water temperature and ice cover thickness in winter. Being a case study, the model was used to simulate the operation process of Jingshi canal, parts of the middle line of South to North water transfer project in winter. The simulation results showed that the change of ice cover roughness, parameters of PID controller and controller logics had big influences on hydraulic response of canal system. The study shows that the computer simulation model can be used to analyze the response of long distance water transfer control canal system during ice forming period.