Abstract: The color controlling method and its realization of single DMD colorized video displaying system were studied in detail. Based on analyzing the advantages and shortcomings of three types of DMD projection system, spatial gray-level modulation and temporal gray-level modulation, one single DMD colorized video displaying system was proposed. The color controlling method based on pulse selection gray-level modulation was analyzed deeply. In this method, the frame-period was evenly divided into R, G, B section, and each of the R, G, B sections was divided proportionally to be some bit-time sections. In every bit-time section, the status of micromirror in DMD was controlled according to the bit value of corresponding pixel gray-level. Considering that the data sent to DMD was the bit-plane data of video pixels, the format conversion from image gray-value to bit-plane data was analyzed in detail. At last, considering the feature of DMD, the operating scheduling was given. The whole scheme is doable. The analysis could provide academic basis for the realization of the system.