Abstract: Featured by scientific analysis and methodological precision, quantitative legislative evaluation has been widely endorsed by legal researchers and professionals at home and abroad. However, existing implementation of quantifying legislative evaluation in China suggests that various gaps exist between its conceptualization and operationalization, manifested in numerous errors in the process of legislative evaluation. For example, the tendency of “de-instrumentalization” and the confusion of basic arithmetic application scenarios, common data collection errors and improper introduction of performance assessment tools in the practice of assessment have brought many obstacles to the application of legislative quantitative assessment. In this regard, the legislative evaluators should correctly judge the premise of the application of the legislative quantitative evaluation norm and avoid the improper application of the legislative quantitative evaluation method.