The invention discloses an automobile cruise control system and method and belongs to the automobile manufacturing technical field. The automobile cruise control system comprises a first micro processing module I which is connected with an engine ECU (Electronic Control Unit); the first micro processing module I is connected with a cruise switch; the engine ECU is connected with a second micro processing module II through a CAN (Controller Area Network) bus; the second micro processing module II is connected with a speed sensor. The automobile cruise control method comprises receiving a speed signal through the second micro processing module and transmitting the speed signal to the engine ECU through the CAN bus; receiving a control signal and a clutch signal and an exhaust braking signal through the engine ECU and performing analysis on the signals; controlling the speed state through the engine ECU according to the control requirements when the cruise control conditions are met and transmitting a cruise control state signal to the second micro processing module II to control the working state of an indicator lamp. According to the automobile cruise control system and method, the problems of the automobile cruise control and abnormal prompts can be solved.