Rare-earth doped fibers are an important means of expanding the wavelength band of optical fibers. Currently, researchers aim to broaden the working wavelength band of optical fibers by doping with different rare-earth elements, thereby increasing the amount of information that can be transmitted. In this paper, a bismuth-doped fiber laser operating around 1300nm was designed. A basic physical model for implementing a bismuth-doped fiber laser was proposed based on the energy levels and transition processes of bismuth, rate, and power propagation equations. It was possible to determine the link between pump power and laser power at a wavelength of 1300 nm by modeling tests using the physical model. Additionally, the relationship between pump light and laser power in bismuth-doped fiber at different positions and propagation directions was analyzed. Suggestions for the future large-scale application of bismuth-doped fiber lasers around the 1300nm wavelength band were provided.