Aiming at the disadvantages of the terahertz mixer test method, such as single function and low-test efficiency, this paper proposes a terahertz mixer sweep frequency test method based on the sweep test method of microwave mixer. This method can increase the test band from microwave band to terahertz band above 110GHz, and realize the frequency sweep frequency test of conversion loss and return loss of the terahertz mixer. Furthermore, the“signal generator + spectrum analyzer”test method and the test method proposed in this paper are used to verify the 150 GHz-170 GHz fourth-harmonic mixer. The results show that the sweep frequency test method proposed in this paper not only achieves the rapid measurement of conversion loss and return loss of the terahertz mixer, but also agrees with the conversion loss measured by the“signal generator + spectrum analyzer” test method, which is of great significance to the test application of the vector network analyzer in the terahertz band.