The invention provides a motor vehicle brake device of a clutch and brake system. A fit linkage principle and a structural principle of a clutch system, a brake system and an acceleration system, and arrangement and operating methods of a clutch pedal, a brake pedal and an acceleration pedal are provided. During motion, the brake system is linked with the clutch system and independent of the acceleration system; during the motion, the clutch system is not linked with the brake system and independent of the acceleration system; the clutch pedal and the brake pedal are operated by the left footof a driver; and the acceleration pedal is operated only by the right foot of the driver. Meanwhile, the invention provides an optimized scheme, in which the brake pedal and the clutch pedal are integrated into a clutch and brake pedal; the upper half travel of the clutch and brake pedal finishes the motion of a clutch, while the lower half travel begins and finishes the motion of the brake system; and the clutch and brake pedal is operated by the left foot of the driver, while the acceleration pedal is operated by the right foot of the driver, so the device is simple and clear, safe and reliable, easy to learn, remember and operate, and extremely low in maloperation rate. Meanwhile, the clutch and brake pedal is designed to structurally comprise a clutch pull rod and a brake pull rod.