Cumbersome equipment and complex algorithms are usually introduced in building an entire surgical system. These constraints will usually make the system less efficient, and not suitable in real surgical environments. In order to provide the physician a clear view of the locations of the lesions, an mixed reality approach to image-guided surgery is proposed. Our system integrates the medical imaging information obtained pre-operatively into the space of the real operation scene. The coordinates of medical images is integrated with a realistic dummy head model using the proposed Improved Alignment (IA) algorithm. In this way, we can help the physician, during the operation, to confirm the path of the operation and to verify the location of the lesion, thereby reducing the risk of the operation and improve the overall safety and accuracy.