The physical and chemical characteristics change of polymer under irradiation environment was analyzed. The irradiation damage and recovery property for polymethylmethacrylate (PMMA) optical fiber under γ-ray irradiation were researched experimentally. The visible light transmission spectrum and recovery property of the POF under different irradiation dose were measured. Under different irradiation dose the light transmission rate was reduced by different ratio. The measured spectrum indicated that the POF irradiation damage and recovery were dependent on wavelength, and the visible light transmission rate of the POF at the range of 400 nm to 550 nm comparing 600 nm to 800 nm, decreased seriously under the irradiation dose exceeded 5 kGy. But under lower dose below 1 kGy, the transmission rate decreased identical at the whole visible light range.