Abstract: At home and abroad for cast-in-place piles of underwater concrete quality inspecting method are many, such as the low strain reflected wave method, high strain dynamic test method, the single pile vertical static load compression test, core method, ultrasonic transmission method et al. Each method has its scope of application and limitations. Ultrasonic transmission method and compared with other methods, this method is of high precision, intuitive and reliable results, is suitable for large diameter pile, the pile of super-long pile testing, therefore, in cast-in-place piles integrity testing, has been widely used, especially in the bridge piles, extend, almost all use the sound wave transmission method of large diameter pile detection. In this paper, a construction site of large diameter piles of ultrasonic transmission method is investigated, through waveform and image contrast, better ltrasonic transmission method was verified test super-long and large diameter effect of these measures. In this paper, a construction site of large diameter piles of ultrasonic transmission method is investigated, through waveform and image contrast, better ultrasonic transmission method was verified test super-long and large diameter effect of these measures.