The coated pipe is widely used in the petroleum, the chemical industry, and other fields because of its advantages of insulation, high-pressure resistance and vibration resistance. To ensure the safe operation of the coated pipe during service, it is necessary to detect its flaws. However, the high polymer material with high sound absorption and attenuation characteristics is usually used as the coating layer of the coated pipe, which makes the traditional high-frequency ultrasonic guided wave detection methods have low signal-to-noise ratio problems. On the other hand, the low-frequency ultrasonic guided wave can travel a long enough distance, but it has the disadvantages of large detection blind areas and low resolution. For this reason, a high-sensitivity method based on nonlinear ultrasonic zero-frequency wave low attenuation is proposed to detect the flaws of coated pipe. Firstly, the generation mechanism of nonlinear ultrasonic zero-frequency wave propagating along the pipe structure was theoretically analyzed. Then, the propagation characteristics of nonlinear ultrasonic zero-frequency wave in free and coated pipe are investigated through finite element simulation and experimental verification. Finally, the notched defects in the coated pipe are successfully detected by using a nonlinear ultrasonic zero-frequency wave in the experiment. The results show that the nonlinear ultrasonic zero-frequency wave has a low attenuation characteristic, and the nonlinear ultrasonic zero-frequency wave can still accurately identify multiple defects in the coated pipe when the linear fundamental frequency ultrasonic wave has been completely attenuated. The nonlinear ultrasonic zero-frequency wave in the method has the characteristic of low attenuation because the carrier frequency is zero, and can be used in the nondestructive testing of the circular pipe structure with high attenuation of the coated layer.