Background: Craniofacial resection (CFR) has been regarded as the gold standard for paranasal sinus and nasal cavity (PNSNC) neoplasms. The improvement of surgical procedures has been ongoing in recent years. We analyzed the clinical curative effects of the function-preservation therapy that was mainly using nasal endoscopic surgery along with appropriate radiotherapy and chemotherapy as applicable. Methods: We performed a retrospective analysis of factors that influence the survival time of the 28 patients with PNSNC neoplasms who underwent nasal endoscopic surgery. All patients with tumor lesions underwent a complete resection in en bloc or piecemeal resection. Five cases did not undergo radiotherapy or chemotherapy; the remaining 23 patients had multimodality therapy. Results: The median follow-up time was 41.5 (range = 14–97) months. The overall 3-year survival rate was 78.57% for T3 cancer and 50% for those with T4. T classification (P = 0.031) and multimodality therapy (P = 0.038) were independent prognostic factors for postoperative 3-year survival rate of patients with PNSNC neoplasms. Conclusion: Function-preservation therapy based on the minimally invasive endoscopic resection (MIER) with appropriate adjuvant therapy not only prolonged the overall survival time but also provided an opportunity to preserve organ function at the same time, which helped to improve the patients' quality of life.