The invention provides a method and system for collaboratively treating medical waste and domestic garbage. The method comprises the following steps of carrying out high-temperature steam treatment onthe medical waste, wherein stream used in high-temperature steam treatment is supplied by a waste incineration system; carrying out compatibility on the medical waste subjected to high-temperature steam treatment and the domestic garbage, and then incinerating jointly the medical waste and domestic garbage; collecting condensate liquid generated during high-temperature steam treatment, and then introducing the condensate liquid into a penetrant treatment station for joint treatment with a domestic garbage penetrant; and transferring waste gas generated during high-temperature steam treatmentto a garbage pit for joint treatment with existing waste gas in the garbage pit. According to the method and system for collaboratively treating the medical waste and domestic garbage, coupling between medical waste high-temperature steam treatment and domestic garbage incineration can be achieved, so that system investment, occupied areas and running cost are effectively reduced, and economic andsocial benefits can be improved as well.