Objective To establish a quantitative index system for risk assessment of postoperative pneumonia in surgical wards, and construct a risk assessment model of postoperative pneumonia based on quantitative index system. Methods The quantitative assessment index system for the severity of postoperative pneumonia was initia-lly developed through literature research. Fifteen domestic experts in the fields of healthcare-associated infection, clinics and nursing were selected and invited for consultation by the Delphi method. Indexes were screened with threshold method. Weight of indexes was determined through analytic hierarchy process. A risk assessment model for postoperative pneumonia was constructed based on risk matrix. Results The positive coefficients of experts in two rounds of consultation were 93.33% and 100%, the authority coefficients were 0.842 and 0.891, and the coordination coefficients were 0.370 and 0.425. The index system for the severity of the consequences of postoperative pneumonia included prolongation of mechanical ventilation, prognosis of postoperative pneumonia, prolonged hospital stay, increased medical expenses, ventilator dependence, mortality of postoperative pneumonia, and increased ICU visits due to postoperative pneumonia. The risk matrix was constructed using the index system of postoperative pneumonia incidence and severity of consequences. Conclusion The risk assessment model of postoperative pneumonia constructed based on the analytic hierarchy process and risk matrix provides an objective basis for the quantitative evaluation of the risk in healthcare-associated infection.