The invention provides an air-coupled ultrasonic high-energy detection method and system. The method comprises the steps that ultrasonic waves emitted by a transmitter transducer are emitted into one face of a detected part at a directional angle alpha, are sequentially reflected by the surface of the detected part and the surface of the transmitter transducer and are emitted into the detected part again, wherein the detected part is of a platy structure; a receiver transducer is arranged on the other face of the detected part at a directional angle theta. According to the air-coupled ultrasonic high-energy detection method and system, excited signals and picked signals both achieve high energy on the condition that no more power energy is needed, influences of environmental noise is effectively inhibited, and the detection accuracy is improved; meanwhile, the positions of the transducers do not need to be precisely adjusted deliberately, the fault-tolerant capacity in the detection process is improved, and good adaptability is achieved.