Abstract: Objective: Skin fit and dosimetric indices of 3d-printed and conventional tissue compensation membrane (TCM), and their advantages and disadvantages when applied for postoperative breast cancer radiotherapy were evaluated, providing a reference for clinical applications. Method: Seventy six patients who received radiotherapy in Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital after radical mastectomy between November 2018 and December 2022 were randomly selected. These patients were assigned into a 3d-printed group and a conventional group, each containing 38 patients. Three-dimensional reconstruction of the air gap between the body surface and the TCM for each patient was conducted, and t tests were used for statistical analyses. Results: The mean total air volume values of the 3d-printed group and the conventional group were 14685.79 mm³ and 103828.18 mm³, and their average maximum air gap heights were 5.71 mm and 20.44 mm. The skin fits in the 3d-printed group were better than those the conventional group (P<0.001). The target conformity index (CI), homogeneity index (HI), ipsilateral lung dose (V₃₀, V₂₀, D_mean) and skin dose (V_100%, V_98%, V_95%, D_mean) of the 3d-printed group were 0.7629, 0.1063, 22.23%, 27.32%, 1514.93 cGy and 95.54%, 97.62%, 98.78% and 5231.66 cGy, respectively, while those of the conventional group were 0.7249, 0.1248, 24.14%, 29.24%, 1588.74 cGy and 92.36%, 95.84%, 97.92% and 5206.19 cGy. The dosimetric distribution in the 3d-printed group was better than that in the conventional group (P<0.05). No significant difference was observed for V5 of ipsilateral lung between the 3d-printed and conventional groups (P>0.05). Conclusions : 3d-printed TCM is superior to conventional TCM in terms of skin fit and key structural dosimetric indexes, demonstrating significant advantages in clinical application.