In order to keep drill out of breaking in the micro-drilling process, a real time monitoring and controlling system for micro-drilling was built based on virtual instrument technology. The system took IPC as main controller and used the Holl current sensor to monitor the spindle motor currents. The sampled data were processed by software written in LabVIEW language, which the functions such as the virtual oscillograph, the virtual spectrum analyzer, the digital filter etc. were implemented. In the experiment taking the spindle motor currents as monitoring objective, the monitoring and controlling threshold was determined according to the relationship between the failure distribution function and the reliability function of the drills. When the monitoring value exceeds the threshold given, the feed motion is forced to backward and a warning is given to indicate tool changing. The experimental result shows that the system together with monitoring and controlling method is able to effectively avoid drill breaking and increases the usage of the micro-drill.