For flour automatic filling and weighing production requirement, this paper innovatively introduces a kind of flour filling weighting mechanism, which has realized its automatic weighing applications by designing variable impulse integral control. A piecewise high-speed impulse is designed by applying the PLC controller high-speed impulse output function, which drives stepper motor resolving production control. Namely, a constant decreasing high-speed impulse is designed infinitely approaching the integral control function to achieve accurate weighing process in precise weighing phase. This control design have effectively restrained system disturbance, step motor high frequency vibrating and overweighting less than 3 g. Compared with the traditional powder automatic weighing control application, the designed control system has no parameters setting and the accurate weighing time is shorter, and it is more convenient to be realized by programmable logic controller (PLC). The weighing accuracy is more approaching the resolution of weighing sensor.