Diamond wheel grinding machining is essential for the accuracy and efficiency of the large scale optical lens. Monitoring system is the indispensable part of the new generation grinding machine for the high demand of the reliability and stability. This paper is dedicated to the intelligent monitoring system of the precision grinding machine. PXI platform of National Instruments Corporation is used to acquire processing signals during machine operating and grinding. PXI controller is connected with the numerical control system of the machine, and the internal sensor signals and the processing parameters can also be output to the monitoring system. All the dynamic and static data related to the machine are stored and managed by the monitoring system database. Thermal error of the machine is acquired by the monitoring system and compensated for high machining precision. Grinding fluid circle system is also monitored and the numerical control system can give alarm for the emergency. Grinding wheel performance is real-time predicted which can give reliable guidance for wheel dressing.