Objective: To observe tbe therapeutic effect of application of San Zi Powder according to selection of time for prevention and treatment of asthma. Methods: 200 children with asthma were randomly divided into 4 groups which were treated with acupoint application of Chinese drugs either according to selection of time or not according to selection of time for 3 years respectively. And they were followed up. Results: Acupoint application of San Zi Powder according to selection of time could improve clinical symptoms and pulmonary function

regulate immune state of the organism. and raise serum immunoglobulin contents

with the total effective rate of 85% which was significantly higher than that of the control group （P<0. 01）

and no toxic or side effects was found. Conclusion: Acupoint application of Chinese drugs according to selection of time can effectively prevent and treat asthma.