We design a single fiber quasi-single mode all-fiber laser oscillator based on single-end 915 nm semiconductor laser forward-pumping, which produces 2.02 kW output power at 1080 nm. We study the relationship among the gain fiber length, stimulated Raman scattering (SRS), and the output power theoretically and experimentally. We optimize the length of the gain fiber to achieve a laser with a high SRS suppression ratio of 0.8 %, which has an output power of more than 2 kW. The optical to optical conversion efficiency of the laser oscillator is about 70%, and the power fluctuation is less than ±1% within 180 min running. The fiber coiling technique is adopted to effectively depress the high-order laser modes to obtain a quasi-single-mode laser (beam quality factor M2≈1.5) at the maximum output power. What is more, the application of the laser in laser cutting is investigated.