This paper deals with the study of size segregation of particles where the size difference causes characteristic movement of particles inside granular media according to the induced vibration. In this study, segregation of particles due to the difference in size is simulated using Cellular Automata. A connected lattice automaton is introduced in the model, so that the variation of particle sizes as well as geometrical arrangement between particles can be represented. The Cellular Automata model can produce various characteristics which are observed in the actual granular systems. Furthermore, it is known from both numerical and experimental observations that the segregation progress is dependent on the amplitude of excitation as well as the particle size ratio.