This study examined the casting analysis of fuel pressure regulator of LPI vehicles. We aims to predict all the phenomenon accompanied by flow and solidification in die casting, and maximize productivity and quality through optimal casting design. As a result of comparing Types A and B of casting design, it was found that the number of overflow affected flow, flowspeed and solidification temperature. And there was a minute difference between solidification temperatures at thick section of the spare parts. Solidification began at temperatures of $624^{circ}C{sim}630^{circ}C$ but after the casting was completed, temperatures at the center of the parts were $600^{circ}C{sim}614^{circ}C$ Temperature of molten metal showed optimal flow at temperature of $680^{circ}C$. It began to solidity around at $650^{circ}C$ and to be cooled between $580^{circ}C{sim}550^{circ}C$ in high speed. When the process was analysed through a computer simulation, it was found that hardness of regulators manufactured through Type B of overflow was above $H_R60$.