Individual microcredit loans involve large quantities and small amounts and necessitate rapid approval, therefore making simple and fast application approvals rather critical. Creditors must evaluate clients' credit status and default risk within the shortest time when determining whether to approve or decline their applications, preventing overdue responses that negatively impact bank profits and management practices, and could trigger domestic financial crises. This study investigates client credit quality criteria, focusing on the expert opinions of bank managers. The decision-making trial and evaluation laboratory method is adopted to enable a comparison and analysis of the similarities and differences in how banks evaluate their clients' character, ability, financial capability, and collateral. Based on causality and correlations among the criteria, we also identify the core problems and key improvement criteria in the evaluation system. Through survey results of professional managers from Taiwanese banks, this study uses the DEMATEL method to compare the differences in bank evaluation methods based on the four dimensions of clients' character, ability, pockets, and collateral, as well as the corresponding 14 criteria. In order to improve the reliability and usefulness in bank client credit risk assessment, the assessment dimensions and indicators of bank client credit risk assessment are first discussed; second, the causal relationship and degree of mutual influence between different dimensions and criteria are researched and assessed; in the end, the paper discusses how to improve the function and the benefits of bank client credit risk assessment.