The demand for police’s ability to identify lies in investigation activities is increasing day by day, but the exploration of training ways for police college students to identify lies has not yet been formed. The traditional METT lie recognition training abroad is based on the classic JACBART micro-expression recognition test and lacks ecological validity. The ecological micro-expression recognition skill training takes seven basic expressions of calm, anger, disgust, fear, happiness, sadness and surprise as the background, and six other micro-expressions except calm as the recognition objects, and examines the same expression under different intensities and different types of expressions with the same intensity. Taking police cadets and on-the-job policemen as training objects, the research results show that EMETT training with different backgrounds and intensities can effectively improve the students’ ecological micro-expression recognition ability, and the effect is not significantly different from that of ordinary policemen. Therefore, it is possible to establish a training system for police cadets’ ability to recognize lies based on EMETT ecological lie recognition training, improve police cadets’ ability to recognize lies, and train practical police talents.