The invention discloses a device and method for automatically molding an emulsified asphalt mixture test piece. The device comprises a plurality of raw material barrels, a stirrer, a mold and a control box, wherein an electronic valve is arranged at an outlet of each raw material barrel; an inlet of the stirrer is connected with outlets of the raw material barrels through delivery pipelines; the mold is arranged under an outlet of the stirrer, and is provided with a striking device for striking asphalt mixture in the mold and removing redundant asphalt mixture; the control box is connected with the electronic valves, the stirrer and the striking device, and is used for controlling the working states of the electronic valves, the stirrer and the striking device respectively. According to the automatic molding device, stirring equipment and an automatic control system are combined to be used for automatically adding raw materials for emulsified asphalt mixture according to set values and accurately controlling dosage of raw materials of the test-piece, compact is not requirement for molding of the emulsified asphalt mixture test piece by utilizing the characteristic of strong fluidity of emulsified asphalt, and the emulsified asphalt mixture test piece can be manufactured more conveniently and efficiently.