Abstract: OBJECTIVE To investigate the effects of the levels of platelet and inflammatory factors and Th1/Th2 ratio in children with bronchial asthma complicated with infectious pneumonia, so as to provide guidance for clinical treatment. METHODS A total of 74 cases of patients with bronchial asthma complicated with infectious pneumonia in the hospital from Jan.2014 to Dec.2015 were selected as observation group, 63 cases of children with acute bronchial asthma were set as control group 1, and in 80 cases of children with infectious pneumonia at the same period were set as control group 2. The patients of the three groups were given routine and symptomatic treatment, and the changes of indicators levels of the three groups before and after treatment and treatment of children were observed. RESULTS After 7-day treatment, the total efficiency rate of observation group was 89.19%, which was lower than 98.41% and 97.50% of control group 1 and control group 2 (P<0.05), the observation indexes before and after the treatment of the three groups had significant differences (P<0.05), the PLT, PDW, TNF-α, IL-6, Th1 cells, and Th2 cells of observation group before and after treatment were all higher than those of control group 1 and control group 2 at the same period (P<0.05), and MPV, IL-12 and the ratio of Th1 / Th2 were lower than those of control group 1 and control group 2 at the same period (P<0.05). CONCLUSION Platelet index, inflammatory factors and Th1/Th2 ratio were closely correlated with bronchial asthma complicated with infectious pneumonia. The results of routine treatment can improve the immune status, platelet index and inflammatory factors, but the effect is not satisfied. In the treatment process, paying more attention to the detection or improvement of these indexes may be the new indicators to guide the prognosis, and also be possible to improve the