Dynamic projection mapping is an interactive display technology, which is capable with multiplayers with naked eyes for augmented reality. However, the fixed and shallow depth-of-field of the projector optics limits its potential applications. In this work, a high-speed projection mapping method with a dynamic focal tracking technology based on a variable focus lens will be illustrated. The proposed system included a high-speed variable focus lens, a high-speed camera, and a high- speed projector, so that the depth and rotation information would be detected and then served as feedback to correct the focal length and update the projection information in real time. As a result, the information would be well-focused projected even on a 3D dynamic moving object. The response speed of the high-speed prototype could reach around 5 ms, and the dynamic projection range covered from 0.5 to 2.0 m.