Objective: To analyse the effects of low and conventional tidal volume mechanical ventilation on the treatment of children with severe pneumonia. Methods: 100 cases of children with severe pneumonia from June 2013 to June 2015 in our hospital were randomly divided into control group and observation group, each of 50 cases. The control group children with traditional tidal volume, tidal volume of 10~12 mL/kg; the observation group children using low tidal volume, tidal volume of 6~8 mL/kg, clinical parameters of two groups during treatment were analyzed. Results: The mechanical ventilation of the observation group was significantly more than that of the control group (t=11.0770, P=0.0000), the mortality rate of observation group was significantly higher than that of the control group (χ2=5.4825, P=0.0192). In the course of treatment, children mean airway pressure (Paw), fraction of inspiration O2 (FiO2), positive end expiratory pressure (PEEP), peak inflating pressure (PIP) and other clinical indexes of two groups had no significant difference (P>0.05), recurrent respiratory tract infections survival rate between the two groups had no significant difference (χ2=0.0624, P=0.8028). Conclusion: For children with severe pneumonia mechanical ventilation, the effect of traditional tidal volume shows better than low tidal volume.