An object-oriented robot programming and simulation environment(ORPE) developed by the authors, which is being used for design and simulation for a variety of robot work cell and manufacturing process, is introduced. The system architecture based on hierarchies of distributed process provides the computing platform for a layered programming structured that models work cell tasks as a set of software objects. These objects are designed to support model-based programming, and support the mechanisms such as inheritance and polymorphism which allow the system to be reusable, extendable, reliable, and portable. And an object-oriented task simulation language used for describing the tasks of active machines is also introduced.