The invention belongs to the technical field of pavement material, and more specifically relates to a totally-enclosed zero-discharge device used for continuous production of modified asphalt, and a method. The totally-enclosed zero-discharge device used for continuous production of modified asphalt is composed of an asphalt pump, a forced feeding machine, a reciprocating-type single-screw mixing machine, a single-stage high-shearing emulsifying machine, a combined-type static mixer, and a multistage high-shearing emulsifying machine which are connected via pipelines; totally-enclosed zero-discharge continuous SBS modified asphalt production is realized via controlling the temperature and the rotating speed of the above equipment. The totally-enclosed zero-discharge device is capable of changing conventional SBS modified asphalt production technology, and producing qualified SBS asphalt from matrix asphalt from a storage tank; the production process is totally closed; no waste gas is discharged; the technical route is refined; operation is simple; occupied space is small; matching with an asphalt concrete mixing station is extremely convenient to realize, and simultaneous startup-shutdown of the totally-enclosed zero-discharge device with the asphalt concrete mixing station is realized; the amount of produced SBS modified asphalt can be controlled based on requirements; influences of a plurality of times of transportation and repeating heating on asphalt and modified asphalt are avoided; energy is saved, and consumption and cost are reduced.