Automobilerakeystem is oneofthe most importantand attractive research areas in automotive industry. anti lockrakingystemaredesignedtoobtaimaximumdeceleration, decreaseitoppingdistance, increasein stability and Automobile handlingandalso loweroscillatioforoccupants comfort. The maiurposeofthe anti lockrakeystemitoreventwheels fromlockingandto adjustthe longitudinallidingithe desiredrangeiorderto createmaximumrakeforce. So far, various control methods have been proposed for the anti lock braking system, some of which have failed to perform well in different road conditions due the existence of many uncertainties. In this research, the braking system of a passenger car in a straight path and in a turn has been investigated and its main purpose is to optimize the braking deceleration of the car in order to reduce the stopping distance. Therefor, the components of the braking system including the booster, main cylinder, hydraulic circuits and wheel cylinder are modeled. Furthermore, fuzzy controller with two inputs (slip and slip derivative) and single output (pressure change) is designed as a controller of anti lock braking system. The half-car model is used which each wheel being controlled individually. The vehicle braking deceleration in the direct path is selected as an objective function. Also, a number of parameters of the braking system components, all of the membership functions and rules of two fuzzy controllers of front and rear wheel are chosen as design variables. Finally, the braking system and its two controllers are optimized by using the genetic algorithm method. The results show that the optimized braking system works well on roads with different coefficients of friction and also has a better performance in the straight path and in a turn while the braking distance is significantly reduce. Keywords: antilock brake system, optimization, genetic algorithm, deceleration, stopping distance, traight path, braking in a turn