In order to realize flexible simulation enviroment which satisfies both fast computation and software productivity improvement, a concept of advanced hybird simulation is proposed which will be realized by incorporating the following two hardware/software developments. One is Module-based Simulation
System (MMS) as a simulation support enviroment and the other is a shared-memory-type parallel computer CX-1 as a back-end processor to a main frame computer to improve computation speed in solving partial differential equations numerically. The capability of the communication software between CX-1 and host computer is extend so that control and communication of CX-1 can be written by FORTAN77 programing on host computer, thus CX-1 program being integrated into MMS. A demonstrative practise of a hybird BWR reactor core simulator is conducted using CX-1 as hardware module to solve neutron diffusion equations in two-dimensional space numerically.