Based on the investigation of the XNOR/OR logical expression and the propagation algorithm of signal probability, a low power synthesis algorithm based on the XNOR/OR logic is proposed in this paper. The proposed algorithm has been implemented with C language. Fourteen Microelectronics Center North Carolina (MCNC) benchmarks are tested, and the results show that the proposed algorithm not only significantly reduces the average power consumption up to 27% without area and delay compensations, but also makes the runtime shorter.