In this study, we propose a linear polarized fiber laser based on the radiation mode of a 45°-tilted fiber grating (45°-TFG). The laser is constructed using a ring resonator structure and a fiber Bragg grating, and an all-fiber single-polarized laser output based on the radiation mode of the TFG is realized for the first time. The experimental results show that when the input pump light power is greater than 24 mW, a stable laser output can be achieved. The central wavelength of the output laser is 1553.45 nm, that of a 3-dB bandwidth is 0.05 nm, degree of polarization is up to 99.8%, and slope efficiency of the laser system is 10.79%. Simultaneously, with the help of the temperature sensitivity of the fiber Bragg grating, the central wavelength of the output can be continuously tuned from 1553.21 nm to 1554.03 nm, and the tuning sensitivity is 11.37 pm/℃.