According to the microwave test requirements of RF multi-port devices, a four port electronic calibrator based on RF MEMS switch with a working frequency in the range of DC~12 GHz was designed based on SOLT calibration principle. The numerical simulation results showed that the return loss of the device was less than 015 dB in the short circuit state. In the through state, the insertion loss of the device was less than 05 dB, and the isolation between ports was greater than 20 dB. In the open circuit state, the return loss of the device was less than 03 dB, and the isolation between ports was greater than 25 dB. At the same time, the load resistance was prepared by micro surface machining process and magnetron sputtering process. The tested resistance was about 50 Ω, which met the design requirements. The designed four port calibration device based on RF MEMS switch had the advantages of good RF performance, small volume and easy to integrate. It could meet the application requirements of X-band microwave multi-port devices in on-chip testing.