Abstract: The present disclosure generally relates to a reactor, in particular to a multiphase interface reactor applicable to chemistry, chemical industry, food, medicine, cosmetics and other fields. The reactor comprises a reaction cylinder; at least one feed port opened in the reaction cylinder; a stirring device, at least a part of the stirring device being located inside the reaction cylinder; at least one cylinder including a first cylinder and a second cylinder, wherein, the reaction cylinder, the first cylinder, and the second cylinder communicate with each other; an annular space is formed between the reaction cylinder and the second cylinder, so that at least part of a reaction product is allowed to enter the annular space from the reaction cylinder, and enter the first cylinder from the annular space; and at least one discharge port arranged on the first cylinder.