Dynamic assessment is currently a research hotspot in the field of education measurement. However, in the study of quantitative assessment in this field, there are remarkable limitations in traditional psychological assessment mode, which hinders the application of dynamic assessment in ESL teaching practice. This paper proposes a dynamic assessment model (LEA Model, short for Learning Efficiency Assessment Model) constructed on Markov chain, which takes the students learning differences as the prerequisite, and shows distinct advantages in the aspects of individuality of assessment subject, dynamics of experiment, the application of LEA model in dynamic assessment is verified, thus introducing this model into dynamic assessment process and prediction of students learning potential. Based on a college English vocabulary classroom teaching assessment provides a scientific quantitative assessment tool for teaching practice.