Erbium-doped fiber lasers have wide applications in fiber communication, fiber sensors, coherent detection and combination because of its narrow linewidth and low noise. An erbium-doped fiber laser with ring cavity is constructed by a self-designed π phase-shifted fiber grating and a high-reflective fiber Bragg grating (FBG), which can achieve narrow linewidth erbium-doped fiber laser output in 1.5 μm-band by utilizing the π phase-shifted fiber grating as a narrowband filter. When the pump power of 980 nm diode laser is 5 W, the laser output power is 1.006 W, the optical to optical efficiency is more than 20%, and the central wavelength is 1549.45 nm with laser linewidth of 5.32 pm. The output light is without residual pump, which indicates that the laser power can be further increased by increasing pump power. High-efficiency, high power, single-longitudinal-mode laser can be achieved by optimizing the bandwidth of transmission peak of π phase-shifted fiber grating, the reflectance spectrum of FBG, and the structure of the laser cavity.