Pico-projection　displays　are　the　main　developing　direction　for　future　projection　displays,　but　the　balance　between　the　optical　efficiency　and　the　system　size　is　still　a　big　concern.　This　paper　presents　a　pico-projector　design　based　on　micro-LED　(mu　LED)　light　sources.　Firstly,　based　on　the　analysis　of　the　characteristics　of　mu　LED,　a　highly　integrated　microlens　array　is　designed　to　improve　the　system　efficiency　by　reshaping　the　spatial　light　distribution.　In　addition,　the　matching　relationship　between　the　aperture　angle　of　projection　lens　and　the　divergence　angle　of　mu　LED　is　studied,　and　on　this　basis,　a　set　of　four-piece　spherical　lens　group　is　proposed　to　achieve　compact　size.　Simulation　results　show　that　the　mu　LED　equipped　with　the　microlens　array　can　concentrate　about　86%　of　the　light　energy　within　a　dispersion　angle　of　+/-　20　degrees,　thus　increasing　the　light　energy　utilization　by　about　3.5　times　and　reducing　the　size　of　the　pico-projector　to　30.18　mm(3).　The　designed　pico-projector　has　high　performance　and　compact　size　with　great　potential　for　future　applications.