In this study an online monitor and control system was developed and tested based on virtual instrument environment for combine harvester automation. A data acquisition system and control elements were integrated into a self-propelled combine harvester. The following online information was recorded: performance parameters (threshing drum torque, engine speed, operation speed, etc), machine settings (reel speed, knife speed, drum speed, etc) and guidance information. The collected data were integrated into windows-based software for real-time processing. Image sensing information was used for swath detection and obtained results could be transmitted to the actuator for auto steering. The guidance error could be controlled in the range of 0.15 m during road surface test with centerline. The ground speed was adjusted by using the threshing power consumption data to improve work performance during field test. Experiments results indicated that it was possible to use virtual instrument environment based system to monitor operation data and conduct other real-time applications for field operation.