Abstract: The irradiation tests by electron, proton and ⁶⁰Co-γ sources are completed for the laser diodes, PIN photo detector, erbium-doped fiber amplifier (EDFA), and silica fiber used in space laser communication systems. The slope efficiency of laser diodes is slightly decreased after irradiation by electron and γ ray, and the value is correlated with the total ionizing dose. The optical power is seriously degraded after the electron irradiation, indicating that the electron irradiation causes more damage than that by the γ ray doses, which can be attributed to the displacement damage induced by the electrons. The dark current and capacitance of the PIN photodetector increases notably after the proton irradiation, which leads to deep-energy level defects in the semiconductors, impairing the performance of the laser diode through a reduction in the minority carriers' diffusion length. The radiation hardness of the EDFA is determined by the erbium-doped fiber. The gain and the noise of the EDFA system become very bad when the erbium-doped fiber is irradiated under ⁶⁰Co-γ. The silica fiber's radiation damage is mainly determined by the total dose effect, and the loss of the optical power degreases with the increase of the optical wavelength. In addition; minor dose rate effect is observed, allowing a flexible choice of an appropriate dose rate within the limit of the experimental conditions. The research results can provide a reference for the selection of components, the evaluation of radiation effects, and the radiation-hardening design for the space laser communication systems.