Objective To study the effect of programmed death molecule 1 (PD-1) PD-1 ligand (PD-L1) inhibitor combined with conformal intensity-modulated radiotherapy on survival time and adverse reactions of patients with advanced rectal cancer. Methods Totally 136 patients with advanced rectal cancer in our hospital were selected between May 2015 and February 2018 and were randomly divided into observation group (PD-1/PD-L1 inhibitor combined with conformal intensity-modulated radiotherapy) and control group (conformal intensity-modulated radiotherapy), with 68 cases in each group. The efficacy of the two groups was compared, and the disease-related factors ［fatty acid synthase (FAS), tumor M2 pyruvate kinase (TuM2-PK)］ and quality of life ［Karnofsky Performance Scale (KPS), Quality of Life Scale (QOL)］ were compared between the two groups before treatment and after 3 months of treatment. The survival rate and occurrence of adverse reactions were compared between the two groups. Results There was no significant difference in efficacy between the two groups (P＞0.05). After 3 months of treatment, the levels of FAS and TuM2-PK in observation group were significantly lower than those before treatment and those in control group during the same period while the scores of KPS and QOL were significantly higher than those before treatment and those in control group during the same period (P＜0.05). The first-year survival rate and the second-year survival rate of observation group were significantly higher than those of control group (P＜0.05). There was no significant difference in the third-year survival rate between the two groups (P＞0.05). There were no significant differences in the occurrence of adverse reactions between the two groups (P＞0.05). Conclusion PD-1/PD-L1 inhibitor combined with conformal intensity-modulated 〖JP2〗radiotherapy can significantly prolong the survival time and improve the quality of life of patients with advanced rectal cancer.