Triplet energy migration in poly[(9-phenanthrylmethyl methacrylate)-co-(methyl methacrylate)] films has been investigated by phosphorescence spectroscopy. Phosphorescence spectra from tripler tl-ap sites were slightly shifted toward the low-energy side with a rise in temperature. The energy migration rates in these systems are complicated, since the trap sites have various energy levels depending on the amplitude of interaction energies, The kinetic analysis was made on the basis of Bassler＇s model in which the site energies have a Gaussian distribution. The fitting procedure well reproduced the phosphorescence decay data in the temperature range 15-100 K, indicating that the concentration of the supertrap increased steeply with the motion of the matrix polymer.