Objective To study the intervention effect of montelukast on thymus and activation-regulated chemokine(TARC) in the children with asthma.Methods 100 children with asthma were randomly divided into montelukast (LTRA) group ( n = 50) and budesonide (BUD) group ( n = 50), the LTRA group was treated with montelukast, the BUD group was treated with budesonide,50 children without asthma as control group were inhaled NS.Before and after 7 days treatment,the asthma symptoms, FEV1,concentration of TARC were measured.Results Before treatment,the concentration of TARC in asthma group was significantly higher than control group (P < 0.05 ).After treatment, the concentration of TARC in BUD group and LTRA group was significandy decreased( P < 0.05 ), but the difference between these two groups was not significantl( P > 0.05 ), the concentration of TARC in control group was not significantly decreased(P > 0.05 ) ;the symptoms were better after treatment in BUD group and LTRA group,(P <0,05) ,and the pulmonary function was significantly improved after treatment in BUD group and LTRA group ( P < 0.05 ).Conclusion TARC was the important factor in children asthma.Montelukast could block the production of TARC ,and was more convenient and safe for children asthma.