Objective To investigate the occurrence and influencing factors of adverse reactions of perioperative blood transfusion in patients with rectal cancer.Methods Fifty-four patients with rectal cancer who received perioperative blood transfusion and experienced adverse reactions to blood transfusion in Wenchang People's Hospital and Haikou Affiliated Hospital of Central South University Xiangya School of Medicine from January 2018 to June 2022 were selected as the observation group.Sixty patients with rectal cancer who did not have adverse reactions to blood transfusion during the same period were assigned to the control group.The basic and clinical data of the two groups were collected.Logistic regression model was established to analyze the influencing factors of perioperative adverse reactions of blood transfusion in patients with rectal cancer.Results The main adverse reactions in the observation group were fever and allergy.The patient with fever and allergic reaction was not found,and no hemolytic reaction occurred.There were no significant differences in the types of adverse reactions caused by the number of transfusions,composition of transfused blood,underlying diseases,allergic history,or the interval between blood transfusion and transfusion among patients in the observation group(all P>0.05).The incidence of allergic reactions was higher than that of fever reaction in patients with history of blood transfusion(P<0.05).The proportions of patients with blood transfusion history,allergy history,number of transfusion>2 times and interval between blood transfusion and transfusion≥0.5 h in the observation group were significantly higher than those in the control group(all P<0.05).The results of Logistics regression model showed that history of blood transfusion,history of allergy and transfusion times>2 were risk factors for adverse reactions of blood transfusion,and the interval between blood transfusion and transfusion<0.5 h was a protective factor(P<0.05).Conclusion Before blood transfusion treatment,it is necessary to strengthen the understanding of the clinical data of rectal cancer patients,pay attention to the patients with blood transfusion history,allergy history and more blood transfusion times,select blood products according to actual demands,and minimize the interval between blood transfusion and transfusion,so as to reduce the adverse reactions of blood transfusion.