Abstract: Aiming at the kinematic modeling of bevel-tip flexible needle,this paper simplifies the bicycle model proposed by WebsterⅢet al for the nonholonomic system of the needle,and presents the bicycle front wheel model and back wheel model.Based on this,according to the actual path and the error analysis,a novel bicycle model with retrace is proposed, which is more suitable for the actual condition.The least square method is adopted to fit the experiment data and the model parameters are obtained.Results show that the bicycle model with retrace is much superior to the bicycle model without retrace,and the front wheel model with retrace is superior to the back wheel model with retrace.The maximum error and the root mean square of the model are small enough to fit the actual path well.