Aim at the distributed measurement requirements of high-speed rotating equipment, a single-channel fiber optic rotary joint(FROJ) is designed and its performance is tested. Based on single-channel FROJ, four-channel FROJ is designed by magneto-optical switch, and its insertion loss is tested under static and dynamic conditions. The experimental results show that the insertion loss of the four-channel FROJ is less than 4.5 dB, the rotation variation is less than 2 dB, and the reliable optical signal transmission can be realized when the speed does not exceed 600 r/min.