In order to solve the problems of heavy weight and large volume of thermal control systems for the aerospace applications， in this study， a PTC （Positive Temperature Coefficient） material based on RT-vulcanized silicone rubber was synthesized via the solution blending method. The composite comprised RT-vulcanized silicone rubber as matrix， and carbon black （CB）， carbon nanotubes （CNTs）， and nickel （Ni） as conductive fillers. Additionally， various additives were incorporated into the composite. To evaluate the material''s performance， its resist-temperature characteristics and automatic temperature regulation capabilities were assessed， confirming its PTC effect and temperature control efficiency. Furthermore， the microstructure of the material was analyzed， leading to the proposal of a theoretical model for the cross-linking expansion structure. The results demonstrate that when the filling amount of CB/CNTs/Ni mixture is 16wt%， the room temperature resistivity of the composite material is significantly reduced to 19.95 Ω·cm， exhibiting a high PTC strength of 4.73. Additionally， after undergoing 300 cold and hot cycles， excellent heating and temperature control performance of the composite are preserved. Thermogravimetric （TG） analysis demonstrates that the incorporation of CB/Ni/CNTs significantly enhance the thermal stability of silicone rubber. Scanning electron microscopy （SEM） reveals that CNTs with a high aspect ratio exert a notable inhibitory effect on the agglomeration of carbon black （CB）. X-ray diffraction （XRD） analysis indicates that the dispersion of conductive fillers within the silicone rubber matrix is relatively uniform. Based on the analysis of microstructure， the internal conductive network channels and structural changes are compared and analyzed， and an analytical model of factors affecting the PTC effect is constructed， which provides a feasible reference for solving the problem of weight reduction of the thermal control system in the field of aviation.