High-speed tape transport mechanisms directly driven by take-up and supply reels are adopted as the large-scale external storage systems or the high-speed search systems of the video cassette recorders and so on. In this paper, the kinetic model of the mechanism is introduced. The relations between the dynamic characteristics and the mechanical parameters are simulated numerically and proved experimentally. In order to improve the frequency characteristics of the servo system, original servo systems are employed newly and the high performance is obtained.