QVGA liquid crystal on silicon microdisplay chip is designed by using D/A converter constructed with comparators and counters, which reduce power consumption and design difficulty of the chip. A QVGA microdisplay video driver system is designed, and a video driver board is built using a CPLD as the central control unit. Video system receives VGA signal output by computer and processes the signal by the control unit to implement the row and column transform and drive LCoS microdisplay chip to display video signal. Test result indicates that gray scales response of the pixel is correct and voltage level meets the requirement of liquid crystal material. The microdisplay chip can display 60Hz 320×240 dynamic video, the display response is fast, and design requirement of display function is satisfied.