Based on the prototype model test of the open diversion channel used for flow discharge and navigation during the construction of Cuijiaying junction, we study the erosion-deposition variation in the channel and analyze the effect of the protection works and the rationality of the protected range according to the flow regime and velocity in different discharges. These research results show that the protected works are stable in general, and these protection works are very effective, especially the works for bank slope, almost none of them are destroyed; Some toe protection works in the downstream of the channel are destroyed badly, so the protected range of theses works should be widened for the stability of the bank slope; Moreover, the protected range in the downstream of the channel can be properly extended.