Notwithstanding the advancement of software engineering for enterprise applications, the process of software implementation is still time-consuming and error-prone. This situation is more severe when developing the custom software, because the requirements are always changing during the whole development processes. This issue could be alleviated by reusing exiting code or services in the private and public repositories. Nevertheless, the reuse could fail if no existing service is matched or existing services could not be composited to satisfy the requirements. Eventually, the developers have to implement the business logic manually for the un-satisfied requirements. In this paper, we present an approach which can automated generate business logic from requirement model for enterprise applications. Unlike other works, our approach does not need to specify design model such as sequence diagram, the business logic could be directly generated from operation contracts of requirement model. Operation contracts only contain the preconditions before executing the action, and the postconditions after execution. Moreover, the generated off-the-shelf code is adopted the same multi-layer structure as Java EE and .NET platforms which are robust, scalable, and widely used in enterprise application developments. Finally, a case study of library management system demonstrates the feasibility and efficiency of the proposed approach in our implemented RMCode tool.