Abstract: Objective: To evaluate three-step method of blood gas acid-base disturbance analysis in training junior nurses in emergency department. Methods: The two groups of nurses who were trained three-step and six-step method,respectively, analyzed 5 cases by herself/himself on the day of training, recording the time and the analyzing results. After a week, the two groups of nurses analyed another 5 cases. We observed the understanding and forgotten status of the two methods. Results:The mean time of analyzing a case through three-step method was shorter than that of six-step method, and there was significant statistical difference between the two group (P<0.01). The average time of six-step method after a week was longer than that before a week (P<0.01) and the error rate of six-step was higher than that of three-step and the results had significant statistical difference (P<0.01). Conclusions: The three-step method of blood gas analysis is more suitable than the classic six-step method to train junior nurses in emergency department.