Silicon carbide(SiC) devices characterized by high efficiency, high power density and wide bandgap, have great potential in many advanced applications, such as electric automotive, aviation and military. Thermal management, condition monitoring and life estimation of SiC modules are essential to achieve high reliability. These control techniques require realtime monitoring or estimation of the module's junction temperature. This paper proposed a thermal model based on an integrated negative thermal coefficient(NTC) thermistor in SiC modules. The Finite Element Methods simulation results showed that the parameters of the thermal model are invariant under different heat dissipation conditions and ambient tem-peratures. The combination of the proposed thermal model with the reading of NTC sensor realized the online estimation of the junction temperature. The accuracy of the thermal model and the independence of thermal impedance were verified by simulation and experimental results.