Abstract: X80 pipeline steel is widely used in pipeline transportation. Semi-automatic welding is mostly used in actual pipeline welding, which inevitably leads to welding defects and stress concentration in the process of use, resulting in major accidents such as pipeline rupture and oil leakage. In order to promote the application of electromagnetic ultrasonic residual stress detection in pipeline steel, this paper tested the best parameters of residual stress detection in X80 pipeline steel by electromagnetic ultrasonic system. The test results show that the accuracy of electromagnetic ultrasonic residual stress detection system was 60 MPa by choosing 6th echoes signal. The relationship between stress coefficient/signal-to-noise ratio (SNR) and echo times in electromagnetic ultrasonic residual stress detection was obtained through experiments. There is an optimal value between echo times and stress coefficient/SNR, and some suggestions were put forward for electromagnetic ultrasonic residual stress detection in thin and thick plates.