Abstarct: Haptic rendering is a formidable challenge in virtual reality space. It refers to the process of generating forces from information provided by the computer, which are executed by the haptic device to create a realized tactile object the user can feel. Considering haptic rendering algorithms for simulating surgical soft tissue interactions, when user move the surgery tool, he must feel force feedback of interaction between virtual tool and virtual tissue and see the effect of tool on tissue. So, correctly model of soft tissue, make interaction fidelity. In literature, authors suggest different methods for deformable object modeling in this simulation. A method with high speed and good accuracy in the object modeling is used. A network of masses, springs and dampers is applied but tool modeled with a point or with a line that reduce the simulation accuracy. This research tried to innovate a 3 DOF mass-spring-damper model by using a fuzzy rule baxsed expert system to simulate rigid tool and deformable object interaction as two superquadrics. Moreover, system's stability is improved, baxsed on virtual wall and the virtual coupling, saturation and energy compensating algorithms. The maximum user's hand's speed and virtual object's stiffness is calculated while demonstrate stability in that direction.