【Objective】 To observe the efficacy of salmeterol/fluticasone(commodity name:Seretide) in the treatment of children with moderate and severe asthma. 【Method】 Evaluate the efficacy by lung ventilation function and clinical asthma control of the 46 moderate and severe asthmatic cases from our outpatient department and the hospital during January 2009 and March 2010 treated by Seretide. 【Results】 1)Significant improvement on the lung ventilation function was founded after 3 months treatment by Seretide. Before the treatment:FEV₁、PEF,FEF₂₅ ,FEF₅₀,FEF₇₅,MMEF_75/25were (1.31±0.59),(3.05±1.33),(2.39±1.17),(1.30±0.69),(0.52±0.28),(1.08±0.60) L/S;after 3 months treatment, FEV₁,PEF,FEF₂₅,FEF₅₀,FEF₇₅,MMEF_75/25 were (1.90±0.59),(4.45±1.35),(3.80±1.17),(2.34±0.80),(0.98±0.39),(2.10±0.82) L/S(t=4.80,5.02,5.78,6.67,6.57,6.80;all P<0.001);of which 28 patients (60.9%) lung ventilation function returns to normal, a abnormal 7 cases (15.2%), two anomalies in 4 (8.7%) ,3 of abnormal in 5 patients (10.9%), four and five abnormal each 1 cases (2.2%), and six indexes abnormal 0); 2)87%(40 cases )of children were clinical controlled , 8.7% (4 cases)of children were partially controlled, 4.3% (2 cases)were not controlled. 【Conclusions】 Seretide can significantly improve moderate and severe children asthma clinical symptoms, lung ventilation function. So, it is an ideal treatment of the older children, moderate and severe asthma, to be worth of clinical application.