Abstract: The motion and deformation characteristics of the catheter play an important role in VR simulation of catheter ablation of atrial fibrillation.Based on the bending mechanism,an improved hybrid mass-spring model is presented and the real-time software system of catheter ablation is developed.The model divides the catheter into several nodes,which are linked by springs with the same length.The model considers the main mechanical properties of the catheter,such as spring force,damping force,bending force,as well as contact force due to collision with the heart.The system can simulate the motion and deformation of the catheter,and the electrophysiological mapping of the left atrium.The simulation result shows that the behavior of the catheter matches the practical situation,which can satisfy the doctor's training requirement.