This paper presents a simulator for Forward Collision Warning and Avoidance (FCWA) system. The proposed simulator is composed of a personal computer as a controller, a 24 GHz radar, a warning and brake lamp, a buzzer and a lead vehicle model which is driven by two AC servo motors. A FCWA algorithm determines the warning and braking headway distance by road surface condition (wet/dry), following vehicle velocity, and relative velocity. The simulator has been designed and used to test a FCWA algorithm under realistic operating conditions in the laboratory. Even failure situations which would normally not be feasible for real vehicle test can be tested in the simulator.