The invention discloses a preparation technology of far-infrared cotton fiber. The preparation technology comprises the steps of preparing raw materials, treating the raw materials, preparing a far-infrared mixed solution, carrying out coating treatment and spinning. The preparation technology is simple in method; the far-infrared coating mixed solution is prepared by mixing far-infrared ceramic powder with a resin bonding agent, a cross-linking agent, a dispersing agent and the like; the treated raw material fiber is coated with the far-infrared coating mixed solution, and the far-infrared coating mixed solution is firmly combined with the raw material fiber, so that the far-infrared fiber is good in effect. An ultraviolet light absorber is also added to the far-infrared coating mixed solution and is dipped into the cotton fiber, so that the finished product fiber has an ultraviolet resistant function. The cotton fiber is refined by alkaline biological enzyme, and alkali treatment is replaced, so that the preparation technology is low in damage to fiber and is beneficial to maintaining fiber strength; apocynum venetum fiber and activated carbon fiber are added into the raw material fiber for use, so that the finished product fiber also has a good antibacterial effect.