Nowadays the quick development of computer technology has made it possible to simulate the transformation processes in the materials in a complex way, by approximating more and more the physical reality. The recrystallization is one of the most frequently simulated transformation process. Of the simulation methods the classical Cellular Automation and the Monte Carlo method [1] has been used by most of the research workers. Our aim has been to develop such an automation which is based on known physical principles and is suitable for the calculation and display of grain structure in the monophase material between hot rolling.