The invention provides an F-P (Fabry-Perot) cavity strained quantum well laser with low linewidth. The F-P cavity strained quantum well laser comprises a substrate (1), a buffer layer (2), an n type lower limiting layer (3), a lower waveguide layer (4), a lower barrier layer (5), an active layer (6), an upper barrier layer (7), an upper waveguide layer (8), a p type upper limiting layer (9) and an ohmic contact layer (10) which are sequentially connected. Through the optimal design of the active layer (6), a linewidth enhancement factor generated by interband transition of a quantum well and a linewidth enhancement factor generated by free carrier absorption and band-gap shrinkage can offset mutually, thereby realizing the low linewidth and improving the quality of a light beam of the quantum well laser. The active layer of the laser provided by the invention is made of InxGa1-xAs materials, wherein x is equal to 0.33, the width thickness of the well is 3-5nm, the center wavelength lambda is equal to 980nm-1036nm, and the linewidth of the F-P cavity strained quantum well laser can be reduced by three orders of magnitude in comparison with a quantum well laser. The F-P cavity strained quantum well laser can be used for optical measurement, solid-state laser pumping, laser spectroscopy research and other fields.