Dynamic Assessment and Cognitively Diagnostic are two common measurement modes. The former is concerned with the individual potential development, but fails to explain the psychological substance of the potential ability. The latter is able to measure the cognitive process of the current level, but not the potential. However, Practice requires that we not only pay attention to the potential ability, but also the further psychological interpretation of the potential. The study from the basic psychometric model: MRMLC and MLTM for MS, attempts to build the dynamic assessment program based on cognitive diagnose and puts forward the corresponding statistical analysis method. To confirm the feasibility of the assessment program and statistical methods, a case study of children’s reasoning ability is developed. 182 children, who were selected from Grade four to Grade six in one pirmary school participated in the program of Dynamic Assessment based on Cognitive Diagnose. At last, the statistic method proposed by the study was used to analyze and compare the result of the assessment. The results show that (1) the program of dynamic assessment based on cognitive diagnose can be realized and the statistic method is also feasible; (2) the program proposed by this study can not only measure the potential ability, but also the change of the cognitive component and strategies; (3) the comparison of the different grades display that, higher primary school pupils are better and more adept at using more complex, more effective cognitive component and strategies.