With the increasing demand of social security, intelligent moving target tracking technology play a more important role in video surveillance system. However, current moving target tracking technology works well for single camera situation but always lost targets in multi-camera environments due to the difficulty of object matching. In this paper, we proposed a new collaborative tracking system for moving target based on space-time video fusion .The idea of this system is firstly to register and fuse real-time surveillance video to 3D virtual model with situation awareness, then the space relativity between different cameras and the time relativity of tracking target moving across multi-cameras are extracted. With the help of this space-time information, we can accurately match the moving targets between consecutive cameras and coordinate adjacent cameras to collaboratively track the target by using moving target tracking for single camera. Test results show that our approach can realize continuous tracking for moving objects between multi-cameras with good robustness.