Augmented reality (AR) is widely used in minimally invasive surgery (MIS), since it enhances the surgeon’s perception of spatial relationship by overlaying the invisible structures on the endoscopic images. Depth perception is the key problem in AR visualization. In this paper, we present a video-based AR system for aiding MIS of removing a tumor inside a kidney. We explore several different AR visualization techniques. They are transparent overlay, virtual window, random-dot mask and the ghosting method. We also introduce the depth-aware ghosting method to further enhance the depth perception of virtual structure which has complex spatial geometry. Both simulated and in vivo experiments were carried out to evaluate these AR visualization techniques. The experimental results demonstrate the feasibility of our AR system and AR visualization techniques. Finally, we conclude the characteristics of these AR visualization techniques.