Objective: To investigate the effect of leukotriene levels on the pulmonary function of patients with chronic persistent asthma, and to observe the correlation between concentration of leukotriene E4 (LTE4) in urine and the patients forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) and FEV1 value. Methods: Ninety-six patients of asthma were studied and classified into three groups based on the severity of expiratory airflow limitation: 1) mild persistent asthmatic group (FEV1 >80% predicted) included 40 patients; 2) moderate persistent asthmatic group (FEV1 of 60% to 80% predicted) included 48 patients; and 3) severe persistent asthmatic group (FEV1 <60% predicted) included 8 patients. All patients were used budesonide and formoterol fumarate powder for inhalation. Before treatment and after treatment for 8 weeks, the concentration of urinary LTE4 were detected by ELISA, FEV1/FVC and FEV1 measured by pulmonary function instrument. At the same time, 40 cases of healthy controls were collected to detect the urinary LTE4. Results: 1) urinary LTE4 concentrations in mild, moderate and severe persistent patients were higher than those in healthy control group (P<0.05), and with the severity of the disease, the urinary LTE4 concentration was increased; 2) FEV1/FVC and FEV1 values were negatively correlated (P<0.05) in patients with moderate persistent asthma before budesonide and formoterol fumarate powder for inhalation treatment. Conclusion: The correlation between pulmonary function and leukotriene levels in moderate persistent asthmatic patients was more closely, moderate persistent and severe persistent asthmatic patients would benefit from administrated leukotriene receptor antagonist agents.