Sliding mesh method is one of the most important methods for analyzing transient rotor-stator coupling of centrifugal pump. The shape and position of sliding mesh interface have direct impacts on the calculation results of transient flow field. However, until now there was no uniform view on how to select the sliding mesh interface. A centrifugal pump was taken as study object. Five different sliding mesh interface schemes were used to simulate the transient flow field. Results showed that the average simulation errors of pump efficiencies for scheme I (i.e., the short line-shaped interface close to impeller outlet) and scheme V (i.e., the inverted U-shaped interface surrounding impeller) were both about 1%. The streamlines in meridian plane and velocities in volute inlet for both schemes were in line with existed experimental results. Specially, the scheme V can give more reasonable gradient of velocity in pump chamber, and gain right results of pressure fluctuation in tongue area. Both scheme Ⅲ (i.e., the long line-shaped interface close to impeller outlet) and scheme Ⅳ (i.e., the long line-shaped interface close to base circle of spiral casing) set the pump chamber to a rotating domain, and gave the simulation errors of pump efficiency as 5.2% and 9.2%, respectively, which also resulted in incorrect streamlines in meridian plane. Both scheme Ⅳ and scheme Ⅱ (i.e., the short line-shaped interface close to base circle of volute casing) set the rotating domain close to tongue, and caused shearing action of tongue to be enlarged. The inlet velocities in tongue area were decreased seriously. In summary, the schemes that made the entire pump chamber into rotating domain or made the interface close to the tongue would make the simulation results unreasonable. The scheme taking the inverted U-shaped interface surrounding impeller as interface was suggested. This scheme can guarantee the simulation accuracy and reflect the real characteristics of the flow field.