OBJECTIVE：To study the effects of montelu kast sodium in the treatme nt of pertussis in children. METHODS ：A total of 160 children aged 6 months-6 years with pertussis admitted to our hospital from Jan. 2017 to Jul. 2018 were randomly divided into control group and observation group ，with 80 cases in each group. Control group received routine treatment such as antibiotics. Observation group was additionally given Montelukast sodium granule or chewable tablets orally （granule for age below 2 years old ，taking with warm water ；chewable tablets for age more than 2 years old ），4 mg/d，once a night. Treatment course of 2 groups lasted for 2 weeks. The changes of clinical indexes as clinical symptoms ，clinical efficacy ，the occurrence of ADR ，and lab indexes as lung function [VPEF/VE，TPTEF/TE，FEV1，FVC，FEV1/FVC]，T lymphocyte subsets （CD4+，CD8+ and CD 4+/CD8+） level，immunoglobulin（IgE，IgG，IgA）level，serum leukotriene （LTB4，LTC4，LTD4）level were compared between 2 groups. RESULTS：Compared with control group （80.00％），total effective rate rate of observation group （95.00％）was significantly increased（P＜0.05）；the cough time of spasm ，the echo time of cockcrow ，the blue and purple time of face caused by cough ，the time of vomit caused by cough ，the time of lung rale and the time of hospitalization were significantly shorter （P＜0.05）；new respiratory tract infection incidence of observation group was lower than that of control group （P＜0.05）；but there was no significant difference in the incidence of ADR between 2 groups after treatment （P＞0.05）. The levels of VPEF/VE ，TPTEF/TE or FEV1，FVC，FEV1/FVC，the levels of peripheral CD 4+ and CD 4+/CD8+，serum levels of IgG and IgA in observation group were significantly increased ，compared with control group ；the level of peripheral CD 8+ and the serum levels of IgE ，LTB4，LTC4 and LTD4 were significantly decreased ，compared with control group （P＜0.05）. CONCLUSIONS ：The addition of montelukast sodium to the routine treatment of pertussis can improve clinical symptoms and lung function of children ，regulate immune function of children and inhibit the release of airway leukotrienes ，which has certain clinical application value.