Abstract: Tracer methodology is a kind of evaluation method which is widely used in hospital evaluation in recent years. It has played an important role in improving the quality of service in medical institutions. According to the National Health and Family Planning Commission, "Maternal and Child Health Hospital Assessment Criteria", tracer methodology takes an important position in the assessment of women and children's health institutions. This paper elaborates on the principle and application of PDCA, and concept, classification, characteristics and application of tracer methodology, and provides reference for the evaluation of women and children's health institutions.