Propose: Surgical treatment of advanced intra- and extracranial communicating skull base tumors is challenging, especially for the reconstruction of the large composite defect left by tumor resection. The aim of the study is to evaluate the utility of the free flap reconstruction of the defects resulting from radical resection of these tumors. Methods: The clinical data of 17 consecutive patients who underwent free flap reconstruction for defect left by salvage resection of advanced intra- and extracranial communicating tumors from 2013 to 2019 were retrospectively collected and analyzed. Results: There were 5 squamous cell carcinomas, 4 adenoid cystic carcinomas, 2 basal cell carcinomas, 2 meningiomas, 1 anaplastic hemangiopericytoma, 1 pleomorphic adenoma, 1 osteosarcoma and 1 chondrosarcoma. All patients had recurrent neoplasms, 2 of which had pulmonary metastasis. A modified radical cervical dissection was performed in 6 patients. The anterolateral thigh flap myocutaneous (ALT) flap and rectus abdominis myocutaneous (RAM) flap were used in 15 patients (88.2%) and 2 patients (11.8%), respectively. Complications were seen in 3 of 17 patients (17.6%) with 1 total flap loss. The median PFS duration was 31 months. The 3- and 5-year PFS rate was 0.47 and 0.24, respectively. The mean OS duration was 66 months. The 3- and 5-year OS rate was 0.85 and 0.68, respectively. Conclusion: Free flap transfer is a safe and effective method with acceptable complications, useful for reconstruction of large composite skull base defects after salvage resection of advanced intra- and extracranial communicating tumors. The functional and cosmetic results are satisfying.