Due to the heavy axle load, high traffic volume and high traffic density, as well as the continuous high traffic volume, the number of rail detection increases and the types become more complicated. These factors bring some hidden troubles for the safe operation of the heavy haul railway. The detection rate of the rail head transverse defect by the large rail inspection car, which used in China for the heavy haul railway, can only reach 30%40%. The detection mainly relies on hand push defect detector. Its detection speed is slow and has high requirements on the operator, which bring high safety risk for operator and line. A new type of high speed rail inspection car based on the fast phased array ultrasonic technique is studied in this paper. The new car has some advantages, including the maximum speed of up to 80km/h and functions of intelligent detect classification, realtime alarm and threedimensional visual display. It is compatible with different heavy haul railway profiles. The detection rate, work efficiency and safety protection level are improved. More importantly, it is of great significance to improve the technical level of rail inspection for China′s heavy haul railway industry.