The non-equilibrium relaxation behavior of releasing an initially stretched polymer chain is investigated by scaling calculations and Monte Carlo simulations. Different relaxation dynamics are found for three regions which are the linear, Pincus and model-dependent regimes. The nonequilibrium relaxation time is derived in these three regimes. These results are confirmed by our Monte Carlo data and compared with recent experiments. Detail chain configurations during the relaxation process are analyzed from the simulation data. The time dependence of the size of the chain and the non-equilibrium relaxation are discussed in the light of scaling theories. (C) 1998 Elsevier Science B.V. All rights reserved.