Abstract: For RTPV, As a high-efficiency deep space nuclear power for deep space exploration, RTPVit’s high temperature insulation is one of the key factors affecting the system’s thermoelectric conversion efficiency. A new high temperature MLI using ceramic lattice separator and molybdenum foil reflector was studied. Based on a comparison of the ceramic lattice preparation processes such as sintering, PVD and atmospheric plasma spraying, ZrO₂ lattice with a diameter of 1.5mm, a thickness of 0.1mm, and spacing of 15mm was prepared on molybdenum foil through atmospheric plasma spraying, which was used as 1 unit of MLI. The thermal insulation performance of a 10 units high temperature MLI was simulated. The results show that, its transient and steady thermal insulation performance is better than that of the traditional high temperature MLI. It can meet the insulation requirements of deep space RTPV with little edge heat leakage, no residue generation, and long term resistance to 1 000 ℃ in a small size.