The experiments were done using p+u junction irradiated with 12MeV electron. Pour electron traps were observed in Si layers: A-center E1(Ec -0.19 eV), the divaeancy E2 (Ec -0.24 eV), and E4 (Ec -0.44 eV), and E3 defect level (Ec- 0.37eV). Using DLTS method in conjuntion with the reverse recovery technique, annealing behavior of E1, E4 and E3 traps have been studied. The annealing temperature of the E3 defect is the highest (≈520℃). We get an activation energy for thermal annealing of 1.71 eV with a frequency factor of ～1.5×109s-1. The E3 and E4 defect levels are the principal recombination center that controls lifetime of minorities following irradiation. As the E2 and E4 defect level annealout, however, defect level E3 becomes the dominant recombination center.