Abstract: Microsphere composites represent a class of micrometer-scale spherical composite materials composed of multi-component substances, capable of integrating the properties of various materials. This kind of materials has been widely applied across multiple fields due to their compact size, diverse structural morphologies, selective encapsulation capabilities, and directional transport functionalities. The composition and structural characteristics of microsphere composites are intrinsically linked to their preparation methods. The phase separation method, a key technique for fabricating such composites, is distinguished by the facile recombination of solutes and solvents in precursor solutions and the spontaneous formation of microspheres post-phase separation. Based on this method, a variety of microsphere composite structures can be prepared, including those with internal multiphase structure, core-shell, onion-like, Janus, multi-protuberant, dimpled, fibrous, bicontinuous and phase-reversed structures. Phase separation endows microspheres with composite structures, broadening their range of application scenarios. This paper reviews the principles of phase separation induced by physical and chemical methods such as mass transfer, heat transfer, photopolymerization, and sol-gel reactions. It summarizes the formation structures and mechanisms of microsphere composite materials prepared by phase separation methods and analyzes the advantages and limitations of each phase separation method.