The invention belongs to the technical field of automobile intelligent aided driving and energy control, and relates to a heavy truck prediction energy-saving system based on road terrain informationand a control method thereof. By using the road terrain, the slope and reference speed and like information, a certain speed margin is provided for a controller, so that the fuel consumption of the heavy truck is reduced and the total distance time cannot be increased. The invention is the heavy truck prediction energy-saving system based on road terrain information and the control method thereof.The method comprises the following steps: allowing the truck speed to change in a certain speed margin by using the road terrain information which is mainly road slope information, establishing a target function containing fuel consumption, speed tracking, speed change and brake, solving an optimal control strategy of gear-shifting, and accelerating or braking through a dynamic planning algorithm, thereby reaching the lowest cost, wherein the total distance time cannot be obviously changed at the same time.