Objective To investigate the effects of PCIA and PCEA on postoperative analgesic effect, cognitive function and inflammatory factor expression in elderly patients with gastric cancer. Methods Select 114 elderly patients who underwent gastric cancer surgery in the First Affiliated Hospital of Henan University from April 2017 to April 2020 as the research objects. They were randomly divided into PCIA group (n=57) and PCEA group (n=57) according to the random number table method. The analgesic effect and cognitive function at different time points were analyzed, and the levels of inflammatory factors before and after operation were recorded. Results According to the results of the analysis of variance of repeated measurement data,, the VAS and MMSE scores of the two groups of patients were all statistically significant in terms of time factor, group factor, and the interaction between time and group（F_time=5615.485、13314.578,P<0.05;F_group=315.107、331.138,P<0.05）. At the same time-point, VAS scores in the PCEA group were significantly lower than those in the PCIA group (P<0.05), and MMSE scores were significantly higher than those in the PCIA group (P<0.05). The levels of TNF-α, CRP and IL-6 were significantly higher in 2 groups 24h after surgery than those in the preoperative group(P<0.05). The levels of TNF-α, CRP and IL-6 in the PCEA group were significantly lower than those in the PCIA group 24h after surgery(P<0.05). Conclusion Compared with PCIA, PCEA has a more significant analgesic effect, while reducing cognitive impairment and the expression of inflammatory factors related to stress response.