A method of ultrasonic excitation pulse generation is brought forward for the requirement of concrete structure NDT. For the great attenuation of ultrasonic wave signal, in order to improve detecting system performance and enhance echo signal, the amplitude of ultrasonic excitation pulse must be increased, and the ultrasonic excitation pulse source has been developed with high frequency relay. Its practicality has been validated by the NDT of the two different media of concrete and water. In order to detect concrete structure effectively and subtly, wave packet decomposition technology is used to process and analyze the detecting data. SAFT is used to image, and system sample machine is developed. The detecting image experiments of different concrete structure demonstrate that the system can detect the concrete structure with depth of one meter, and image to display the position of embedded things inside the concrete structure