This paper presents an FPGA-based system that aims to perform three-dimensional multiphase-flow simulations. In this implementation, the immiscible lattice-gas automata (LGA) were selected as the target simulation model. The immiscible LGA are classified as the cellular automata (CA), which are a discrete dynamic model. The simulation box consists of an array of cells. The structure of the box should be chosen carefully since it decides the limitation of simulation behaviors. On the other hand, all the lattice structures should be allocated in order so that they enable us to describe the LGA as stencil computation. Here, we expect that the FPGAs have a great possibility in achieving dramatic speedup. Experimental result shows speedups that achieves two orders of magnitude in the immiscible LGA with the face-centred hyper cubic lattice structure.