A numerical calculation model of the narrow ridge waveguide was established based on the effective refractive index method. The relationship between the polarization characteristics and the transverse mode of the InGaAs quantum well narrow ridge waveguide semiconductor laser was studied experimentally. According to theoretical calculations， the effective refractive index difference of the TM-like mode in the ridge waveguide is larger in the direction of the slow axis. The confinement factors of the TM-like mode are larger than those of the TE-like mode， and the slow-axis high-order mode is more likely to appear. As the height of the ridge waveguide increases， the fast-axis high-order modes are truncated， and the confinement factor of the TE₀₀-like mode gradually increases to be similar to that of the TM₀₀-like mode. The slow-axis high-order mode is suppressed due to its large scattering loss， theoretically achieving high polarization， and near diffraction limit beam-quality laser output. In terms of experiments， a narrow ridge waveguide semiconductor laser with a high polarization extinction ratio and a fundamental transverse mode was fabricated by the gain polarization characteristics of quantum well materials and by designing the height and width of the ridge.