In order to improve the economy and safety of commercial vehicle cruise system, a predictive adaptive cruise control system (PACC) is designed considering fuel saving and safe driving, and the economic speed of the predictive cruise is planned based on the road slope ahead. An optimized predictive adaptive cruise control strategy based on the front vehicle information is proposed to solve the problem of braking disturbance caused by the vehicle in front during cruise. Based on the gradient of the road ahead, the adaptive inter-vehicle distance is designed and the driving speed of the main vehicle is planned to realize the predictive adaptive cruising. A real vehicle test is carried out based on FAW JH6 heavy-duty commercial vehicle. The research results show that the algorithm can effectively reduce fuel consumption and driving fatigue, which provides extremely important theoretical and practical value for the development of commercial vehicle driving assistance system.