The parameter h,in a fuzzy linear regression(FLR) model,determines the probability distribution of the fuzzy coefficients and influences the system credibility of the FLR model.To obtain the functional relationships with optimized h values in quality function deployment(QFD),the FLR model was analyzed,where the coefficients were assumed as symmetric fuzzy numbers containing parameter p.When the parameter p was given,considering both the system fuzziness and membership,the h values were determined according to the criterion of maximum credibility of the system.An illustrative example was provided to demonstrate the performance of the proposed approach.Meanwhile,the optimized h values were obtained under different representatives of p values,namely,the secondary root,triangle and parabolic symmetric fuzzy numbers.The changing disciplines of the system fuzziness and reliability were analyzed with regard to the optimized h values.The maximum system credibility of the functional relationship can be obtained by comparing the corresponding results.