Abstract: For the traditional domestic tractor air brake system, the main trailer service brake control is incompatible; the function does not meet the requirements of EU regulations, such as long braking response time, the driver cannot brake the trailer when the control pipeline is broken, and there is no main trailer at the same time. Parking brake function, etc. Through a lot of research and analysis on the air brake system at home and abroad, the final scheme adopts the hydraulic control air brake valve to realize the compatibility of the main trailer service brake control, and can shorten the braking response time; the solenoid valve is used to realize the simultaneous parking of the main trailer; The trailer control valve with air-controlled air is used to realize the automatic braking function. The dual-pipe air brake system developed and designed has passed the installation test. The pressure value at the handshake joint is above 650 kPa during braking, and the response time is within 0.4 s; the pipeline ruptures and the driver depresses the brake pedal to achieve automatic trailer braking within 2 s.（Brake-Away） function; pull the main driver’s handbrake and the trailer parking brake activates at the same time. The design scheme greatly improves the braking effect and safety of the air brake system of the tractor-trailer.