Aiming at the current sharing control problem of parallel uninterruptible power supply (UPS) system, a novel autonomous control strategy for parallel UPS system was designed. The new scheme can be used for parallel current sharing control of multiple three-phase online UPS modules. Each UPS controller was based on regulating the voltage reference of the filter capacitor as a function of its own output current, enabling independent current sharing control without the need for information exchange between the inverters. At the same time, the controller also guaranteed the control accuracy of the load voltage and the dynamic performance under load disturbance. The experimental platform composed of two UPSs was used to test the new autonomous control scheme. The experimental results show that the controller had good control effects under different load conditions, including step-load and nonlinear load.