Abstract: In view of characteristics of batch process, this paper proposes a new real time and nonlinear minimum window principal component analysis (MWPCA) method based on multiway principal component analysis and nonlinear theory. MWPCA method breaks through linear MPCA modeling with single model structure and innovates in a nonlinear multi-model structure for batch process modeling. The method emphasizes particularly on real-time characteristic in on-line batch process performance monitoring and eliminates error caused by predicting future measurements of process variables, increases the accuracy of process performance monitoring and fault diagnosis. MWPCA modeling procedures,principle and its application are discussed in detail. PVC process performance and fault diagnosis system based on MWPCA method verify the validity of the method.