4 units added into normal saline 100 mL, twice daily. Patients in two groups were treated for 2 weeks. After treatment, the clinical efficacy was evaluated, and the bacterial clearance rates, the improvement of clinical symptoms, serological indexes and serum pulmonary surfactant protein level in two groups before and after treatment were compared. Results After treatment, the clinical efficacy in the control and treatment groups were 80.00% and 95.56%, respectively, and there were differences between two groups (P<0.05). After treatment, the bacterial clearance rates in the treatment group was 86.67%, which was significantly higher than 63.33% in the control group, and the difference was statistically significant between two groups (P<0.05). After treatment, the disappearance time of fever, pulmonary rale and cough in the treatment group was significantly shorter than that in the control group, with significant difference between two groups (P<0.05). After treatment, the hs-CRP, PCT, IL-1β, and sTREM-1 level in two groups was significantly decreased (P<0.05). And the decrease degree in the treatment group was more obvious than that the control group (P<0.05). After treatment, the SP-A, SP-B, SP-C and SP-D level in two groups was significantly decreased (P<0.05). And the serum pulmonary surfactant protein level in the treatment group was obviously lower than that the control group (P<0.05). Conclusion Ulinastatin combined with biapenem can effectively improve the clinical symptoms and reduce inflammatory reaction in treatment of severe pneumonia, and improve the serum surfactant protein, which has a certain clinical application value."/>