〔Abstract〕 Objective To study the clinical application of low-dose heparin in children with severe pneumonia, in order to provide some reference and support for the clinical treatment of children with severe pneumonia. Methods A total of 333 children with severe pneumonia admitted to Shaoguan Maternal and Child Health Care Hospital from December 2017 to March 2019 were selected as the study subjects. According to the random number table method, they were divided into two groups: 166 cases in the observation group and 167 cases in the control group. The observation group selects the routine treatment plus heparin treatment, the control group routine treatment, compared two groups of children with treatment efficient and incidence of adverse reactions, shortness of breath symptoms to eliminate it, cough, eliminate unavailable, lung's symptoms to eliminate it and resume normal temperature, and the children before and after treatment serum c-reactive protein and calcitonin original levels. Results The effective rate of the observation group (92.77%) was higher than that of the control group (76.05%), the difference was statistically significant (P < 0.05). The incidence of adverse reactions in the observation group (10.24%) was lower than that in the control group (25.75%), and the difference was statistically significant (P < 0.05). The times for the elimination of shortness of breath, cough, pulmonary rales and normal temperature in the observation group were shorter than those in the control group, and the differences were statistically significant (P < 0.05). After treatment, serum C-reactive protein and procalcitonin raw water in two groups were decreased on average, and serum C-reactive protein and procalcitonin levels in observation group were lower than those in control group, the differences were statistically significant (P < 0.05). Conclusion Routine treatment is better than routine treatment alone in children with severe pneumonia.