Abstract: A haptic deformation model based on admittance control is proposed for rapid and accurate haptic deformation in virtual sugery simulation. Using the proposed model and two PHANTOM OMNI haptic interaction devices, a prototype system for real-time haptic soft tissue rendering is built upon 3DS MAX 2013, Microsoft Visual C++ 2012 and Open GL, which supports interactive bimanual pulling operations on a virtual heart. It is shown from the perceptional experiments that the proposed model is simple and effective due to smooth visual feedback, stable haptic feedback and realistic deformation effects, and that the perception and interaction between the operator and virtual environment are accurate and reliable. The performance and accuracy of the deformation model are well balanced to satisfy basic requirements of virtual surgery.