A high-resolution microsatellite's focal plane components have high heat flux and a long working time. In order to solve the heat-dissipation problem of a microsatellite's focal plane components under the condition of narrow space, this paper uses a new type of ultralight and super-high thermal conductivity Pyrolytic Graphite Sheet to make a thin and flexible thermal conduction strip. Such a strip is used to design the thermal control scheme for a fully passive, modular, and fast integration of the focal plane components. Analysis and test results show that under the conditions of an installation space of ≤0.5 mm and the mass of the thermal conduction strip of ≤20 g, the focal plane components work continuously for 600 s; the maximum temperature of the CMOS (Complementary Metal-Oxide-Semiconductor) sensor is 31.8°C. Five groups of CMOS sensors had a temperature nonuniformity no higher than 1°C. The application of the new PGS (Pyrolytic Graphite Sheet) provides a new solution for the related space thermal design.