Abstract: Based on the developmental histroy and current advancements of international Mars sample return missions, an analysis of flight mission was carried out, and the necessity of Mars orbital rendezvous and the Earth-Mars transfer flight plan were discussed. On this basis, the key phases of the spacecraft for Mars sample return mission (Mars entry/descent/landing, sampling/encapsulation/transfer, Mars surface take-off and ascent, Mars orbital rendezvous, etc.) and technical difficulties were summarized. Based on typical design schemes home and abroad, the main technical solutions of the key phases were studied.