AUTOSAR is a partnership of automotive manufacturers and suppliers working together to develop and establish a de-facto open industry standard for automotive software architectures. In the AUTOSAR architecture, the runtime environment is at in the heart of the AUTOSAR architecture to provides the infrastructure services that enable communication between software components and between software components and basic software components. The RTE generator is an automated generation tool for AUTOSAR specification based RTE according to the ECU configuration. It generates communication API function for the software components and the basic software components like OS and COM of the application. The availability and the accuracy of the RTE generator are important for the automobile software which is based on AUTOSAR architecture, this paper proposes an architectural design of the RTE generator for auto-generation of the AUTOSAR based RTE.