Real-time dispatching principle is a key technique of open-pit mine truck dispatching system. A new openpit mine truck real-time dispatching principle which is under macroscopic control is proposed in this paper. Its advantages are considering the importance of object truck flow rates given by truck flow optimization substantially and controlling all of the actual truck flow rates to be approximate to current object truck flow rate by taking unloading points as emphasis, and global optimization can be realized better. The simulation research indicates the performance of this principle has a certain advantage compared with the dynamic programming method of DISPATCH system developed by Modular Corporation and an obvious advantage compared with the fixed manual schedule method. The truck dispatching system with this dispatching principle has run successfully in a large scale open-pit mine in the early 2005.