The paper described the method of demolishing reinforced concrete supporting internal large foundation pit by controlled blasting under complicated environment. When demolishing the reinforced concrete under special environment, cutting vibration source in advance, reducing single-section amount of primary explosives and putting up protection shed can effectively control the influence of blasting viboration, flying rock and fugitive dust to surroundings. It has been proved by practice that demolishing steel reinforced concrete supporting internal large foundation pit by controlled blasting is safe and efficient.