With the emergence and development of self-luminous micron-pixel-sized Micro-LED (Micro light-emitting diode, μLED)?, using μLED as the light and image source have become possible for ultra-compact projection optical engines. It greatly simplifies the structure of traditional projection display optical engines. In this paper, a μLED-based super miniature projection optical engine is proposed, and a high image quality pico-projection lens is designed based on 3.302 mm(0.13 in) μLED display chip. The divergence angle of μLED display chip matched with the pupil of pico-projection lens is optimized according to the light distribution characteristics of μLED chip, which effectively improves the light efficiency of μLED based pico-projection optical system. The results show that the volume of the system is only 18.35 mm³, and the MTF value of the center field of view of the projection lens exceeds 0.57 at the cut-off frequency. The μLED based pico-projection display optical engine achieves a good trade-off between system volume and image quality, and has a wide application prospect in near-eye display devices such as AR/VR in the future.