The reptation processes of polymer chains embedded in post arrays are studied by using Monte Carlo algorithm.The simulation results show that the post array with small array spacing can suppress the contour length fluctuation of the polymer chains efficiently so that the relaxation times of the polymer chains coincide with the scaling law given by the reptation theory.However

it can be shown that the reptation in post arrays is slightly different from that in polymer melt by comparing the end-to-end correlation function obtained in simulation with the prediction of reptation theory.The end-to-end correlation functions are underestimated by the reptation theory since the original tube regime can not be fully eliminated by the motion of chain ends in post arrays.The reptation process in post arrays can be perfectly described by the two-dimensional self-avoiding lattice model proposed in this paper.