Background: The reverse shoulder arthroplasty (RSA) may be a promising alternative for proximal humerus tumours because of good postoperative shoulder function. However, the conventional reverse shoulder prosthesis can not meet individual needs and RSA has been associated with a relatively high complication rate. Therefore, implant design and surgical reconstruction technique warrant further study. Methods: Between September 2015 and May 2018, 7 patients were treated via RSA after enbloc resection of the proximal humerus tumours. A 3D-printed guiding baseplate was used to assist the implant of the 3D-printed glenoid prosthesis; a personalized humerus prosthesis was used to reconstruct the proximal humerus. The functional outcomes were assessed by range of motion (ROM) of the shoulder joint, Musculoskeletal Tumour Society (MSTS) functional score, and Toronto Extremity Salvage Score (TESS). We also analyzed tumour recurrence, metastases, and complications associated with the reconstruction procedure. Results: All patients were observed for 14 to 36 months, with an average of 23.6 months. At the final follow-up, the mean MSTS score was 85.7% (range, 73.3-93.3%), and the mean TESS score was 90.0% (range, 84.1-95.9%). No instability, infection, scapular notching, loosening or fracture were observed in this series. One patient with GCT suffered from pulmonary metastasis, while one with osteosarcoma died because of pulmonary metastasis. Conclusion: The 3D-printed guiding baseplate facilitated the accurate implantation of the glenoid prosthesis. The RSA based on a 3D-printed glenoid prosthesis and a personalized custom-made humerus prosthesis significantly improved the shoulder function and decreased the complication rate. Further studies of a larger scale with longer follow-up are required to validate this technology.