Objective. The purpose of the study was to investigate the clinical effect of radiotherapy combined with capecitabine in rectal cancer patients after neoadjuvant therapy. Methods. 80 rectal cancer patients who underwent neoadjuvant therapy in our hospital from February 2016 to February 2018 were selected as the study subjects and divided into the control group (n = 40) and experimental group (n = 40) according to the order of admission. Among them, the control group was treated with radiotherapy, while the experimental group was treated with radiotherapy combined with capecitabine. The therapeutic efficacy, CEA levels, the incidence and recurrence rate of adverse reactions, as well as the progression-free survival and survival rate after 2-year treatment were analyzed in the two groups. Results. The effective rate of treatment in the experimental group of 87.5% (35/40) was significantly higher than 50% (20/40) in the control group, with statistical significance (X2 = 13.09, P < 0.001 ). After treatment, the CEA levels in the two groups both decreased significantly, and the CEA level in the experimental group of 3.75 ± 1.76 ng/ml was significantly lower than 7.35 ± 2.11 ng/ml in the control group, with statistical significance (T = 8.29, P < 0.001 ). The incidence and the recurrence rate of adverse reactions of 5% (2/40) and 10% (4/40), respectively, in the experimental group were significantly lower than those of 40% (16/40) and 30% (12/40) in the control group, with statistical significance (X2 = 14.05, 5.00, P < 0.001 , 0.05). After the 2-year follow-up, it was found that the progression-free survival of 21.53 ± 6.23 months in the experimental group was significantly longer than that of 18.18 ± 5.41 months in the control group, with statistical significance (T = 2.57, P < 0.05 ), and the 2-year survival rate of 97.5% (39/40) in the experimental group was significantly higher than 80% (32/40) in the control group, with statistical significance (T = 6.13, P < 0.05 ). Conclusion. Radiotherapy combined with capecitabine in rectal cancer patients after neoadjuvant therapy can improve the therapeutic efficacy with fewer adverse reactions and longer patients’ survival, which is worthy of popularization and application after neoadjuvant therapy for rectal cancer.