The running characteristics of the single longitudinal mode, single polarization λ/4 phase-shift DFB Yb3+ -doped fiber CW lasers were researched. The fiber laser have the following excellent-characteristics: Output power of 25 mW, fluctuation of less than 2%, 100% single longitudinal mode, 30 dB polarization extinction ratio, 60 dB signal-to-noise. On the other hand, the effect on the fiber lasers is also researched from several factors such as temperature, mechanism perturbation and fresnel reflection of fiber end section.