In this paper, we focus on designing a customizable modular based virtual platform for modeling, simulating and testing telexistence applications, where the physical parameters are preserved in the virtual environment; for motor control of physical characteristics of robot as well as sensory feedback of vision, auditory, haptic. We proposed 'Virtual Telesar' which allows telexistence engineers to model a prototype system before manufacturing it and to experience how the final model will look-like, perform manipulations etc... in real world without building it. The platform consists of three features: first, the user can define a robot using predefined modular components. Second, the user can customize and tune up parameters. Third, the user can have immersive experiences of operating the robot with visual, auditory and haptic sensation. In this paper, we describe a design concept of Virtual Telesar platform and report modeling result based on a physical robot and result of immersive experience with it.