Purpose: This study aimed to investigate the effects of 3D-printed Bolus or conventional Bolus on the dosimetric distribution of target area, dose of organs at risk (OARs) and body surface dose in patients with radiotherapy after radical breast cancer surgery.Methods: 1. A 3D-printed Bolus was made on the basis of the 3D scan data of the body surface contour of the human body model used for radiation simulation. Conventional Bolus and 3D-printed Bolus were used to cover the phantom; computed tomography (CT) simulation, target area and OARs were delineated and an intensity-modulated radiotherapy (IMRT) plan was created. The conformity, uniformity and dose of the OARs were evaluated for comparative analysis. 2. Two patients undergoing radiotherapy after radical mastectomy at the Liaoning Cancer Hospital were selected to produce 3D-printed Bolus on the basis of the 3D scan data of the patient’s body surface. During radiotherapy, the conventional Bolus and 3D-printed Bolus were used for tissue compensation and a radiochromic film was used to measure the optical density (OD) values of the patient’s body surface. The difference in body surface dose between the conventional Bolus and the 3D-printed Bolus was analysed.Results: 1. The conformal index (CI) , heterogeneity index (HI) and dose of OARs of the 3D-printed Bolus intensity-modulated radiation therapy plan of the human body model used for radiation simulation were all superior to those of the conventional Bolus (CI = 0.941 vs. 0.979, HI = 0.134 vs. 0.288). 2. In the two patients undergoing radiotherapy after radical mastectomy for breast cancer, the OD values of the radiation chromogenic film using 3D-printed Bolus radiotherapy were higher than those using conventional Bolus (patient 1: P = 0.047; patient 2: P = 0.016).Conclusions: Compared with conventional Bolus, 3D-printed Bolus has obvious advantages in the target dose distribution of radiotherapy after radical breast cancer surgery and protection of OARs. Thus, it could improve the body surface dose of patients and should be promoted and applied in clinical treatment.