The invention provides a manufacturing method of a low-loss optical fiber and manufacturing equipment. The manufacturing method comprises the following steps of: arranging a water vapor environment out of a fiber drawing furnace; and passing a hot optical fiber generated in the fiber drawing furnace through the water vapor environment after stretching out of the port of the fiber drawing furnace. According to the manufacturing method and corresponding manufacturing equipment provided by the invention, the crystal structure in the optical fiber is improved by way of water vapor annealing, so that the inner crystal structure is optimum, the rayleigh scattering of the optical fiber is reduced, and therefore, the loss is reduced to minimum 0.18db/km.