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Online monitoring of welding path is important as deviation from the welding path will significantly affect the welding quality. This paper proposed a welding path monitoring system using a dual-microphone array for the pulse metal-inert gas (MIG) robotic welding process. A calibration method was developed for microphones to find best locations for collectin arc sound signals. Arc sound features were analyzed to obtain the relationship between the arc sound signal and the welding path deviation. Prediction models for welding paths were then established in two ways: (1) the prediction model was based on individual microphone signals and (2) the model was based on signals from the dual-microphone array which proved to have better prediction accuracy in monitoring the welding path. The dual-microphone model showed its potential advantage in quality monitoring and control for the MIG welding process. The prediction error could reach 0.6708 and 1.1901 mm. The monitoring system based on a dual-microphone array could meet the position accuracy requirement of welding quality control in pulse MIG welding.