Silicon carbide nano-clusters have some promising specific properties for micro- and optoelectronics. In this work the SiC clusters formation and the growth on the silicon (111) surface during molecular beam epitaxy (MBE) have been investigated theoretically with implementation of the rate equations simulation model. The model was successfully applied to obtain the temperature dependence of the cluster concentration. The results were compared with the experimental data [1-3]. Furthermore, influence of the surface reconstruction transition (70) --> (1x1) on the temperature concentration dependence was investigated.