Abstract： To monitor multi-rate processes, a multi-rate principle components analysis algorithm was proposed in which the covariance matrix was calculated using the incomplete multi-rate data samples. To avoid the bias of the covariance matrix, the resampling method was adopted. Besides, the offline modeling strategy and online monitoring strategy were proposed. Then two case studies on both numerical and Tennessee Eastman process (TEP) simulation was given to prove the effectiveness of the proposed algorithm compared to other methods. The result shows that the proposed method has a better performance in multirate process monitoring.