For 3D space assembly of micro-particles, the column cavity assembly of micro-particles with diameter of more than a dozen microns and cavities with diameter of several hundred microns was determined as the research object, and a trans-scale assembly method research of micro-particles in 3D space was developed. Firstly, for the problem that micro-particles are hard to be gripped and released because of micro-force from substrate, the micro-force of micro-particles was analyzed, and a micro-gripper based on theory of vacuum adsorption was designed to grip and release micro-particles. Secondly, for the large-span of size between micro particles and column cavities, its very difficult to realize monitoring of the real-time positions of micro-particles and cavities in assembly process, then a micro-robot system with multi-dimensional visual monitor function was designed and a multi-dimensional visual monitor model was set up to realize on-line monitoring of assembly process of micro-particles and cavities. Lastly, a semi-automatic assembly method of micro-particles and cavities based on multi-dimensional visual monitor model was proposed. Experimental result proves the effectiveness of proposed method, and the aim of putting a micro-particle with diameter of 20 μm into a column cavity with diameter of 200 μm is realized. This method applies to 3D space assembly of micro-particles in micro-electrical-mechanical (MEMS) system fabrication.