Electromagnetic pulse eddy current detection technology is widely used in metal pipeline defect detection because its transient response signal has rich time domain characteristics. However, the rapid attenuation phenomenon of pulse electromagnetic field in space makes the transient response signal susceptible to noise interference. In order to improve the signal-to-noise ratio of the transient response signal in pulsed eddy current testing and realize the pipeline defect detection, this paper optimizes the parameters of the detection coil and proposes a method for metal pipeline wall thickness corrosion defect detection. Firstly, the influence of excitation coil on transient response signal was analyzed by finite element simulation software, and the parameters of excitation coil were optimized. Then, the detection effect of the detection coil on metal pipe defects before and after optimization was studied, the amplitude of the detection signal is increased by 4 to 5 times after optimization. The relationship between the defect detection sensitivity of the transient response signal and the detection signal time was also analyzed, and the defect detection method was given. Finally, through the established pulse eddy current metal pipeline defect detection experimental platform, the defect detection method was verified on the metal pipeline with annular defects. The experimental results show that the defect detection curve obtained by the proposed method has preferable signal-to-noise ratio and defect detection sensitivity at the previous time of the transient response signal, and can be used to evaluate the wall thickness thinning of metal pipes.