Basing on the sampling and recovery theorem, this paper investigates the principle of equidistance subdivision for image sensor export signal by hardware circuit.The mechanism of the hardware equidistant subdivision and the function of the image sensor are analyzed, and the circuit diagram of the hardware equidistant subdivision is given with the export signal of the image sensor. Based this, the simulated experiment is a testing of the laser diffraction pattern by electronic CAD PSpice software. This simulated experiment shows that the method with the hardware equidistant subdivision can improve highly its measured accuracy (especially the device of low bit and big central distance), in Laser diffraction measure fine wire diameters, so this experiment can prove its true of the theoretical analysis. This method also eliminates nonuniformity of the device, to large extent, by low pass filter.