A pixel structure of an active matrix full-color OLED display device and its manufacturing method are provided. The pixel structure of the display device comprises two thin film transistors, a storage capacitor, a color filter, and an OLED device structure constructed on a top surface of a substrate, a black matrix region outside the color filter region and under the thin film transistors. In this pixel, structure of the OLED display device, the OLED device structure and the color filter are integrated in a thin-film-transistor array. This simplifies the process, reduces the leakage of light and increases the contrast of the display device. A white OEL device is used to emit light. A light then passes a color filter to get red, green or blue color of light. Therefore, a full-color OLED is formed. A poly-silicon thin film transistor is used to provide current to the OLED device structure and served as an active drive device. The advantages of the display device include simple fabrication process, high-resolution, high lighting efficiency and wide viewing angle.