Grating coupled semiconductor lasers (GCSLs) has a wide application prospect in many fields, such as optical free space communication, intersatellite communication, ranging for laser radar, atmospheric environmental testing and medical imaging. In order to verify the reliability of GCSLs, the chips in different preparation stages and products of GCSLs are tested based on Raman spectroscopy. It concluded that for unprocessed semiconductor laser chip, the longitudinal optical (LO) photons mode vibration of GaAs chip is strong but the transverse (TO) optical photons mode vibration of GaAs chip is weak. when the is unprocessed. When the surface of GaAs chip is covered by a layer of SiO2 membrane, the LO mode will movetowards long wavelength direction, but its intensity wouldn’t change. When a 100 m mesa is etched on GaAs chip which is covered by SiO2 membrane, LO mode vibration of GaAs chip weakens and TO mode vibration of GaAs chip enhances, and the peak width of LO mode and TO mode increase. After gratings are etched on the 100 m mesa, LO mode vibration of GaAs chip continues to weaken, but TO mode vibration of GaAs chip becomes stronger. It shows that lattice defects exist in the fabrication process of GCSLs. By contrast testson the semiconductor lasers without gratings, it shows that defect peaks present in the Raman spectrum of GCSLs regardless of the defects on light emitting surface. This further proved that the strains or defects were introduced into the fabrication process of grating structure, which affects its reliability, resulting in a decrease of the reliability of GCSLs.