An extended belief rule-based (EBRB) system is superior to existing rule-based systems in managing several types of uncertain information and modeling complex issues effectively and efficiently. However, the accuracy and interpretability of the EBRB system still need to be enhanced by addressing the following shortcomings: the interpretability of the intermediate variables in the EBRB system should be definite and the system parameters must be effectively determined. Therefore, we distinguish discrete and continuous data types to perform sensitivity analysis twice: first, on the rule inference scheme to study the interpretability of individual matching degrees and activation weights; and second, on the rule generation scheme to examine the effect of utility values and attribute weights on the accuracy of the EBRB system. Based on the analyses, we propose a novel activation weight calculation method and parameter optimization method to enhance the interpretability and accuracy of the EBRB system, respectively. We then present three case studies to elucidate the effectiveness of the proposed methods. The results indicate that the enhanced EBRB system prevents counterintuitive and insensitive situations and obtains better accuracies than some studies.