The prevalence of microprocessor-based controllers in automotive systems has greatly increased the meed for tools which can be used to validate and test control systems over their full range of operation. The objective of this paper is to develop a real time simulator of an anti-lock braking system and the methodology of using hardware-in-the-loop simulation based on a personal computer. By use of this simulator, the analyses of a commercial electronic control unit as well as the validation of the developed control logics for ABS were performed successfully. The simulator of this research can be traction applied to development of more advanced control system, such as traction control systems, vehicle dynamic control system and so forth.