Abstract: The vertical drilling tool can achieve efficient vertical and fast drilling by applying transverse active deviation control force to the borehole wall, but it also makes the dynamic characteristics of BHA more complicated, and even causes complex downhole vibration and drilling tool failure. Therefore, it is necessary to study the dynamic characteristics of drilling string by vertical drilling tool. Taking Power-V tool for example, a model of transverse active deviation control force was established initially, and then a dynamic model of drill string was established based on Hamilton’s principle. Later, the dynamic characteristics of drill string with transverse active deviation control force were solved by node iteration method and Newmark-β method. Based on verifying the accuracy of the models, taking a well for example, the whirl trajectory and whirl speed features of drill string were analyzed. The results show that with the addition of Power-V, the drill collar near the vertical drilling tool is inclined to whirl forward on the low side of the hole, and the whirl trajectory of the drill collar center presents an elliptical shape. Meanwhile, the drill string is subject to a great side force, and there is a strong transverse force exerted on bit and stabilizers installation, thus changing the motion characteristics of drill string. The surface torque and downhole speed fluctuate greatly, and the drill string is subject to severe transverse vibration, which is consistent with the downhole measured results and the ground observation results. In practice, measures should be taken to reduce above vibration and improve the efficiency of drilling operations.