The effects of energy transfer on luminescence decay curves are studied. Donor-acceptor energy transfer and donor-donor energy migration are considered simultaneously for solving the problems in previous models. Three models named I-H-B,D-H-B and V-F-B are established here. The RE ions luminescence decay curves of the elpasolite system under different conditions are calculated using the above models. The conclusion is that the V-F-B model is the best. Then the luminescence decay curves from the 4G5/2 state to 6H7/2 state of Sm3+ at 170K in Cs2NaSmxY1-xCl6 for six different concentrations are simulated successfully using V-F-B model.