Ultrasonic welding is considered to be one of the effective ways to join composite materials because of its high efficiency and environmental protection. The ultrasonic welded joint of composite materials may have certain aging effect under different use environments. In this study, the ultrasonic welded joint of carbon fiber reinforced polyetherimide composite (CF/PEI) was taken as the research object. The aging performance of CF/PEI composite ultrasonic welded joint was evaluated by scanning electron microscopy (SEM) observation of single lapping shear strength(LSS) and joint failure morphology under high temperature, boiling and humid heat environment. The results show that the single lap shear strength of the ultrasonic welded joint decreases significantly after storage at a high temperature (110℃-170℃) for 5 hours, water absorption above 1%, and storage at a hot and humid environment (30℃, humidity 50%) for different periods (5-15 days).