Abstract: OBJECTIVE To investigate the clinical efficacy and safety differences of cefmetazole and piperacillin/tazobactam in the treatment of elderly patients with community-acquired pneumonia, so as to provide references for clinical treatment. METHODS A total of 160 cases of elderly patients with community-acquired pneumonia from Mar. 2013 to Mar. 2016 in hospital were chosen, and randomly divided into group A and group B, with 80 cases in each group. The two groups were respectively treated with cefmetazole and piperacillin/tazobactam intravenous infusion, and the clinical efficacy for short-term and drug adverse reactions incidence between the two groups were compared. RESULTS The clinical efficacy for short-term, the disappeared time of clinical symptoms and signs and hospitalization time of group B were all significantly better than those of group A(P<0.05). The pathogenic bacteria clearance rate of group B was significantly higher than that of group A(P<0.05). The immunity indexes levels after treatment of group B were significantly better than those of group A and before treatment(P<0.05). There was no significant difference in the adverse reactions incidence between the two groups. CONCLUSION Compared with cefmetazole, piperacillin / tazobactam in the treatment of elderly patients with community-acquired pneumonia can efficiently relieve the symptoms and signs of respiratory tract, shorten the clinical course of disease, promote the removal of pathogenic bacteria, improve the immune function of body and did not increase the adverse reactions risk.