Abstract: To solve problems of large volume, high power-comsumption, complicated installation at site and off-line diagnosis existed in application of traditional vibration analyzer in coal mine, a novel on-line and mine-used I.S. vibration monitoring analyzer was designed. The working principle and application in coal mine ventilator of the analyzer were introduced. The analyzer uses envelope demodulation technology and quantitative diagnostic identification technology to extract characteristic frequency of fault and make quantization calibration, so as to realize on-line monitoring and fault diagnosis of bearing. The practical application showed that the analyzer can meet with requirements of real-time and accuracy in operation statue and on-line diagnosis of large-scale electromechanical equipments of coal mine, which has a wide promotional value.