Objective:To investigate the relationship of the acute radiation reactions of totalbody irradiation before hematopoietic stem cell transplantation with the different total and fractionated doses of irradiation.Methods:The clinical data of 48 patients who underwent 6 MV X-ray total body irradiation pretreatment from May 2015 to December 2019 in Shijiazhuang Ping'an Hospital before undergoing hematopoietic stem cell transplantation were retrospectively analyzed. The patients were divided into 8 Gy group (12 cases), 10 Gy group (31 cases) and 12 Gy group (5 cases) according to the total radiation dose, and divided into 4 Gy/f group (17 cases) and 5 Gy/f group (31 cases) according to the fractionated radiation dose. Acute radiation reactions in the oral mucosa, pharynx, salivary glands, upper gastrointestinal tract, lower gastrointestinal tract and lung of patients in each group after radiotherapy were summarized and compared.Results:Acute pharyngeal reaction in the total radiation dose of 8 Gy group showed that 11 cases (91.7%) were grade 0 and 1 case (8.3%) was grade 1; in the total radiation dose of 10 Gy group, 10 cases (32.3%) were grade 0, 13 cases (41.9%) were grade 1, 4 cases (12.9%) were grade 2, 3 cases (9.7%) were grade 3, and 1 case (3.2%) was grade 4; in the total radiation dose of 12 Gy group, 2 cases (40.0%) were grade 0, 1 case (20.0%) was grade 1, 1 case (20.0%) was grade 2, and 1 case (20.0%) was grade 3. The severity of acute pharyngeal radiation reaction in the total radiation dose of 8 Gy group was better than that in the 10 Gy and 12 Gy groups, and the difference was statistically significant ( χ2 = 11.338, P = 0.003); there was no significant difference in the incidence of acute radiation reactions in other parts (all P > 0.05). Acute pharyngeal radiation reaction in the fractionated radiation dose of 4 Gy/f group showed that 13 cases (76.5%) were grade 0, 2 case (11.8%) was grade 1, 1 case (5.9%) was grade 2, and 1 case (5.9%) was grade 3; in the 5 Gy/f group, 10 cases (32.3%) were grade 0, 13 cases (41.9%) were grade 1, 4 cases (12.9%) were grade 2, 3 cases (9.7%) were grade 3, and 1 case (3.2%) was grade 4. The severity of acute pharyngeal radiation reaction in the fractionated radiation dose 4 Gy/f group was better than that in the 5 Gy/f group, and the difference was statistically significant ( Z = -2.606, P = 0.009); there was no significant difference in the incidence of acute radiation reactions in other parts (all P > 0.05). Conclusion:The total dose of 8 Gy and fractionated dose of 4 Gy/f in the total body irradiation before hematopoietic stem cell transplantation can alleviate the acute pharyngeal radiation reaction.