Be aimed at engineering application of lightweight thermal protection structure and surface functional coatings in space exploration，research on surface state processing control and characterization of surface functional coatings based on the requirement for direct implementation of low-density weak rigid fiber-reinforced resin-based thermal protection material was conducted. The handheld 3D-Microscopic scanner was innovatively applied to evaluate the surface state， and its application and feasibility was verified in the study. The influence of precision processing parameters on the surface state of low-density weak rigid fiber-reinforced resin-based heat protection material was identified， and optimal parameters for effective control of surface state were determined as follows： step distance of 0.2 mm，rotate speed of 5000 r/min and cutting depth of 0.5 mm. The fiber raised height of machined surface was successfully controlled below 0.2 mm， meeting the surface state requirements for the subsequent direct application of thermal control functional coatings. The research results hold significant engineering value for the development and application of thermal protection technology in space vehicle.