In this paper, we propose a narrow-linewidth random fiber laser based on random distributed grating array to achieve a short cavity length and narrow-linewidth random laser with low pump threshold and high slope efficiency. The random grating based on randomly distributed grating array can effectively improve the pump threshold and pump power of the random fiber laser. Based on the localization theory of light, a narrow-linewidth random fiber laser is constructed with the ultra-narrow relfection peak of the random fiber grating. The laser can generate a stable narrow linewidth random laser output of 1.33 kHz, the pump threshold is approximately 24.5 mW, and the slope efficiency is approximately 10%. Moreover, the central wavelength and laser output power remain stable. Compared with other lasers, the proposed laser has a lower pump threshold, higher slope efficiency, shorter cavity length, and relatively simpler structure. Accordingly, the proposed laser can potentially be applied in several applications, including optical communication, narrow-linewidth high power fiber lasers, and fiber sensors.