Frequency-converter is one of the key technology of the microwave system, however, the key performance indicator of the technology is hard to break through, which is limited by the electron devices. A novel method of microwave mixing based on dual-parallel electro-optic external modulators is proposed in this paper. In this paper, the key components such as mixing technology, electro-optic modulation and optical frequency tupling are designed. Finally, a simple experimental system is built to verify the key parameters, and the system is simulated by using Matlab.