In order to improve the reference of designing of anti clogging ability of labyrinth channel emitter, the sand content and water and sand velocity distribution in the trapezoidal labyrinth channels were analyzed by CFD, the movement trajectories and velocity of solid particles in modified channel before and after tested by PIV. The phenomenon of a large number of solid particles concentrated on the surface near the upstream face and low velocity position of trapezoidal channel emitters. When flow path is being modified, it is appropriate to increase the modification of the upstream face. Combined with the whole flow path and processing requirements, the downstream face may need not modified. Regarded the some one sand content distribution line as the borderlines of trapezoidal channel to design the channel several times, after structural standardization and selecting the wide flow path, the position with high sand content can be canceled, and the better channel model is got. The method tested by CFD and PIV can keep the previous hydraulic performance before modification, and significantly improve the anti clogging performance.