The invention discloses a method for refining bismuth from bismuth oxide slags. The bismuth oxide slags and reduction agents are subjected to reduction smelting, liquation decoppering, primary lead removal through chlorine, vacuum distillation for silver removal, secondary lead removal through chlorine, high-temperature refining for dechloridation, and caustic soda flakes adding for tellurium removal, and finally refined bismuth is obtained. Alloy containing silver, copper, bismuth, lead and the like directly enters the decoppering procedure, wet pretreatment is omitted, the decoppering procedure is simplified, copper matte and silver-zinc crusts are prevented from being generated, the usage amount of nitric acid in a wet section is reduced, emission of nitric oxide in the nitric acid dissolving process is reduced, and pollution to the environment is reduced; after a zinc adding and silver removal technique is changed into the vacuum distillation for physical silver removal technique, the silver-zinc crusts which are difficult to treat are eradicated, physical separation of silver and bismuth is achieved to the maximum extent, and the recovery rate of silver is increased; and the usage amount of coal gas and auxiliary materials is reduced, the labor intensity of workers is relieved, the production period of the refined bismuth is shortened, the production cost of the refined bismuth is reduced, and the direct recovery rate and the recovery rate of the refined bismuth are increased.