Based on flying start and stop principle, a type of open large flux same direction diverting device with high accuracy was designed by using the method of modularization design. The diverting device was composed of modules of three single open different direction diverters with a rotating nozzle and a fixed divider with reversed in and out. After studying and analyzing of working principle, structure and characteristic of diverting flow volume error of the diverting device, under the condition of ensuring the movement repetition at same direction of the nozzle kept consistent and the timer starting/stopping delay was the same, the diverting time were the same and there was no flow volume error. It is no need to solve the optimal timer starting and stopping moment, the diverting flow volume error is unrelated of the factors as diverting speed, the characteristic change of flow field inside the nozzle, the position and shape of the baffle and the splash of the liquid, and etc. The diverter device is suitable for large flux liquid flow calibration facilities.