Saeed Fayaz - Statistics center of Iran, Industrial department, Tehran, Iran
Majid Ebrahimi - Department of Industrial Engineering, Mazandaran University of Science and Technology, Babol, Ira
Ali Gholi Nejad Dowin - Master student of Industrial Engineering, Sadjad Higher Education Institute, Mashhad, Iran

In the case of process capability index several methods are identified. In this paper ,a new process capability index using fuzzy number and fuzzy probability concept, in order to remove the weakness of otherfamous method is suggested. After introduction of fuzzy index in univariate case, fuzzy multivariate process capability index is investigated. Finally, this new method is compared to three well-known methods in literature review, with numerical example

component; Process capability index, Fuzzy number, Multivariate normal distribution