The online detection and monitoring system is applicable to collecting and recording the alarm signals of spark, bump, outer diameter, connector detector and other equipment during the production of wires and cables, displaying the measured values of the outer diameter detector in real time, and generating a trend chart. It can also print the information such as defect type and meter position in real time through a small thermal printer, so as to realize the analysis of production process capability and process index capability, and trace the product quality problems, So as to improve product quality and reduce production costs.