With the growing demand for lightweight and sustainable manufacturing in the aviation industry, thermoplastic composites have emerged as a major alternative to traditional metallic materials due to their high strength, recyclability, and high-efficiency forming characteristics. As a core method for the integrated assembly of thermoplastic composite components, welding technology has thus garnered significant industry attention for its advantages over mechanical fastening and adhesive bonding, including the reduction of fiber damage and enhanced structural integrity. Therefore, this paper systematically reviews the research advances and current applications of thermoplastic composite welding technologies in aviation. It focuses on the process principles, research progress, and aerospace application cases of five key techniques: Laser welding, resistance welding, induction welding, ultrasonic welding, and conduction welding. Additionally, this paper discussed future trends and research priorities for thermoplastic composite welding technologies.