Abstract: With the advancement of surgical techniques and refinement of perioperative management, the long-term survival rate of liver transplant recipients has significantly improved, making the management of de novo malignancy (DNM) increasingly critical. Compared with the general population, adult liver transplant recipients suffered from an approximately 10-fold higher risk of developing DNM and a 2- to 3-fold higher risk of mortality. DNM has become the most common cause of death for recipients surviving more than 10 years after transplantation. To standardize and optimize the diagnosis, therapeutics, and management of DNM in adult liver transplant recipients, the Branch of Organ Transplantation of Chinese Medical Association and Branch of Organ Transplant Physicians of Chinese Medical Doctor Association organize experts to systematically review and analyze domestic and international evidence-based medical data, combined with clinical practical experience in China, and establish the Clinical practice guideline for diagnosis and treatment of de novo malignancy in adult liver transplantation recipient (2026 edition). This guideline elucidates the epidemiological characteristics, risk factors, screening strategies, prevention and therapeutic principles of DNM in adult liver transplant recipients, and proposes a series of scientific recommendations, aiming to improve the post-transplant quality of life and long-term survival rates.