The invention provides a control method and device of a cruise control system, a controller and a vehicle. The method is applied to the controller of the cruise control system. The method comprises the steps that whether the vehicle is in a cruise control driving state or not at present is monitored; when the vehicle is in the cruise control driving state, operation triggering information for operating a cruise switch set of the cruise control system is received, wherein the operation triggering information comprises starting information used for starting cruise control driving or reset information used for setting the target cruise vehicle speed; and according to the preset corresponding relation between the different operation triggering information and corresponding adjustment modes, the adjustment modes corresponding to the operation triggering information are adopted, and the target cruise vehicle speed in the current cruise control driving process is adjusted. The problems that the key function of a cruise switch set of an existing cruise control system is simplex, the number of the adjustment modes of the target vehicle speed in a cruise control state is small, and the use requirements of users are difficult to satisfy are solved.