In pulsed eddy current testing (PECT), the excitation parameters and sensor parameters have a great influence on the detection signal. Analyzing the influence law of different parameters on the detection signal can improve the performance of the detection system by optimizing the design. Based on the principle of pulsed eddy current testing, a test system for measuring the thickness of ferromagnetic specimen was established, and the influence of the number of turns and the inner diameter of the excitation coil on the test signal was analyzed. The test results show that increasing the number of turns and the inner diameter of the coil can improve the resolution of the detection signal. The increase of the inner diameter of the coil and the number of turns of the excitation coil can increase the order of magnitude of the minimum value of the detection signal. The detection thickness range of the sensor can be increased by increasing the number of coil turns and the inner diameter of coil.