There has been a variety wide of hydrological simulation models, each model has its own characteristics. Hydrological modelling considers more and more detailed physical mechanism. And involved professional models also increased great significantly. Therefore, it is particularly important to establish an open unified model interface standards to make a data communication among different models and quickly formulate modelling systems suitable for the characteristics of target watershed. OpenMI emerged at the right moment to satisfy the requirements of above situations. The thesis bases on OpenMI to design hydrological modelling systems and inherits OpenMI framework of design, request/feedback mechanism and hierarchy facing to modules. This design can solve the assembly link problem of cross-language and multi-type models and make a beneficial attempt for hydrological modelling system efficient integration.