The laser source is an important part of a cold atomic clock for laser cooling and atomic population detection. This study selects a 1560-nm fiber laser and a fiber amplifier as the seed laser and the amplifier laser, respectively, in a rubidium cold atomic clock system because of the technical maturity of the industrial products. The cooling laser is obtained at 780 nm by doubling the frequency of the amplified laser using a nonlinear frequency doubling crystal. Further, the laser frequency is locked to the rubidium transition line via the saturation absorption frequency stabilization technique. A part of the cooling laser passes through an electro-optic modulator and an acousto-optic modulator with a frequency shift of 6.8 GHz to obtain the repumping laser. The lasers are provided to the cold atomic clock after ensuring appropriate power distribution. The amplifying, frequency doubling, and noise characteristics of the key components in the laser device are verified. Subsequently, the beating signal between the cooling laser after frequency doubling and the optical frequency comb locked to an ultra-stable laser denotes that the line width of the cooling laser is approximately 74 kHz and that the short-term stability is half an order of magnitude higher than that of the external cavity semiconductor laser which is used in our laboratory. Furthermore, the application of such a laser light source to the cold atomic clock can reduce the limitation of fountain clock stability which can be attributed to the detection of the laser frequency noise.