Objective To evaluate the clinical efficacy of Qingfei Huatan Huoxue Formula（清肺化痰活血方） for severe mycoplasma pneumonia of toxin-heat blocking lung syndrome in children. Methods A total of 78 patients with severe mycoplasma pneumonia of toxin-heat blocking lung syndrome were randomly divided into a control group and a treatment group

with 39 cases in each group. The control group was treated with basic western medicine plus Maxing Shigan Decoction（麻杏石甘汤）

while the treatment group was given Qingfei Huatan Huoxue Formula plus basic western medicine. Both groups were given 1 dose per day for 10 days. Clinical symptoms

physical signs scores

changes in coagulation function and inflammation indicators before and after treatment were compared between groups

and curative effect was evaluated. Results There were 4 cases in the treatment group and 6 cases in the control group falling off. A total of 35 cases in the treatment group and 33 cases in the control group were enventually included. After treatment

the recovery rate of the treatment group was 74.28%

which was significantly higher than 51.51% of the control group（P<0.05）. After treatment

the symptoms and signs of both groups were significantly lower than before treatment（P<0.05）

and the scores of cough

chest X-ray indications and lung signs in the treatment group were significantly lower than those in the control group（P<0.05）; after treatment

prothrombin time（PT）

activated partial thromboplastin time（APTT）

D-Dimer（D-D）

procalcitonin（PCT）

C-reactive protein（CRP） of both groups were significantly decreased than those before treatment（P<0.05）

and PT and D-D in the treatment group were significantly lower than those in the control group after treatment（P<0.05）. Conclusion Qingfei Huatan Huoxue Formula as adjuvent therapy has shown its definite efficacy in treating children severe mycoplasma pneumonia by improving clinical symptoms

signs and coagulation function.