Free radical polymerization and living ion polymerization have been simulated via the dynamic Monte Carlo method with the bond-fluctuation model in this paper. The polymerization-related parameters such as conversion of monomers, degree of polymerization, average molecular weight and its distribution are obtained by statistics. The simulation outputs are consistent with the corresponding theoretical predictions. The scaling relationships of the coil size versus chain length are also confirmed at different volume fractions. Furthermore, the effect of diffusion on polymerization is revealed preliminarily in our simulation. Hence the simulation approach has been proven to be feasible to investigate polymerization reactions with the advantages that configuration and diffusion of polymer chains can be examined together with polymerization kinetics.