Electron irradiation causes atomic displacement damage and produces point defects in semiconductor materials. The formation and variation of defects determine the optical properties of semiconductors during the irradiation process. In this paper, Te-doped GaSb was irradiated by 1 MeV electrons, with fluence of 1 x 10(15) electrons cm(-2), and its optical properties investigated by temperature-dependent photoluminescence (PL) before and after irradiation. After irradiation, the peak position had a blue-shift and intensity was significantly enhanced. The carrier concentration increased from 4.14 x 10(17) to 7.82 x 10(17) cm(-3) but mobility decreased from 2690 to 1780 cm(2) s(-1). These phenomena could be explained by the complex mechanism of defect decomposition, that is, the VGaGaSbTeSb defect decomposed into two independent V-Ga Ga-Sb and Te-Sb defects. To verify this mechanism, undoped GaSb was irradiated under the same conditions and PL results indicated that electron irradiation had little effect on optical properties of undoped GaSb.