The invention belongs to the technical field of unmanned driving and provides a self-adaptive following cruise control method and system. The method comprises the following steps that driving parameters sent by a vehicle-mounted sensor are received; according to safe driving parameters and the driving parameters, a relative parameter ratio M is calculated; the relative parameter ratio is used for representing a difference value of deviation of the driving parameters from the safe driving parameters; and based on relative ratio parameters, the driving parameters of an intelligent vehicle are adjusted to reduce the difference value of the driving parameters and the safe driving parameters. The embodiment of the invention controls the driving speed based on the relative parameter ratio, when the driving parameters are closer to the safe driving parameters, the relative parameter ratio is smaller, the corresponding acceleration magnitude is smaller, and until the acceleration becomes 0, uniform velocity driving is achieved. The driving safety hidden trouble and driving discomfort which are caused by the situation that uniform deceleration driving goes directly into uniform velocity driving are avoided.