Laser diodes (LDs) applied in the space or nuclear radiation environments will be susceptible to the radiation damage, which induces the degradation of the LD performances. In this paper, the radiation experiment progresses of the LDs manufactured at different periods such as the GaAs LDs at forpart, the quantum well LDs, and the quantum dot LDs are reviewed. The degradations of the LD radiation parameters induced by different particles or rays such as protons, neutrons, electrons, and gamma rays are briefly introduced. The key problems needing to be further resolved in the future are analyzed. This paper will provide the basis of the theories and experimental techniques for the investigations of radiation experiment methods, degradation, damage mechanisms, and adiation hardening of the LDs.