In this paper,a dielectric constant measurement system for powder materials is presented,which can work at different temperatures ranging from room temperature to 200℃.This system is developed based on the theory of NRW algorithm using coaxial line. There are two key design factors of this system. One is an improved calibration method to remove the adapter and pads. Another is the temperature distribution is analyzed and optimized using ANSYS thermal analysis to ensure the temperature is uniform in the test fixture and is safe enough to connect to the Vector Network Analyzer (VNA). In this paper,the simulated lunar soil is measured from room temperature to 200℃,from1 GHz to 18 GHz. At different temperatures,the permittivity of simulated lunar soil LLB-07 and lunar soil JSC-1A is very similar. The dielectric constant and loss tangent of simulated lunar soil increase with the increase of temperature. The test system of this paper can be used to test the variable temperature permittivity of powder materials.