Abstract: The noise problem caused by the operation of metro train is becoming more and more prominent. Monitoring metro noise is of great significance to formulating reasonable vibration and noise reduction plans and to alleviating noise pollution. A metro-specific noise online monitoring device that integrates intelligent hardware and open software is developed. The device is based on the NI Compact RIO platform to build a metro noise intelligent acquisition hardware, which can achieve high-precision acquisition, efficient processing and real-time network transmission of metro noise data. Developing client-end software on the LabVIEW software platform enables monitoring data analysis, real-time evaluation, and visual management. The results of field trials on the training line from Longyang Road Station of Shanghai Rail Transit Line 2 to Longyang Road Depot show that the metro noise monitoring device meets the test requirements.