Abstract: To solve the problem of the weak characteristics of rolling bearing under low speed and variable speed, peoposes a multi-periodic cumulative reference correlation coefficient (MPCRCC) schme based on the optical encoder signal to enchance fault features. The characteristics of instantaneous angular speed (IAS) fluctuations caused by rolling bearing faults under different radial loads and velocities are studied, and the fault size estimation of rolling bearings under low-speed is discussed. The interference component analysis of encoder signal under the low-speed and variable-speed conditions is carried out. Based on the IAS signal fluctuation fearures caused by the rolling element bearing fault, combined with the multi-cycle differential accumulation characteristics and correlation analysis characteristics, the MPCRCC method is proposed to realize the fault detect of rolling element bearing fault under the low-speed and variable-speed conditions. The proposed scheme is verified by simulation and experimental, and the effectiveness and robustness of the MPCRCC method are verified by the MPCRCC method under the low-speed and variable-speed conditions.