Abstract: This study aims to reform the teaching of medical vocational English courses through the hidden hierarchical teaching method under the theoretical framework of CBI(Content-Based Instruction). According to the different English foundation and learning needs of students, students are divided into different groups in the form of heterogeneous cooperative groups. Teaching objectives and teaching processes at different levels are set, and corresponding value-added evaluation methods are adopted. In each module of listening, speaking, reading and writing, combined with subject knowledge, the study sets hierarchical tasks within the group to give full play to students'individual advantages which enhances the learning effect. Through this teaching method, the training quality of technical talents can be improved comprehensively, and the goal of improving the quality of vocational education can be achieved.

Key words: Quality improvement, CBI, Hidden stratified teaching, Heterogeneous cooperative group, Value-added evaluation, Medical vocational English