For low temperature poly-silicon(LTPS) active matrix organic light emitting display(AM-OLED),the digital gray scale of sub-field can significantly improves the light uniformity and gray scale accuracy.By increasing the dimension and resolution of the display panel,the driving frequency would increase exponentially.In this paper,by guaranteeing the enough time of lighting for each pixel,the composite ping-pang structure and dual-channel RAM output are introduced,then the colorful dynamic video display is implemented on 12.7 cm QVGA AM-OLED with 16 gray scales.