The invention relates to a compressing device, in particular to a fast and automatic compressing device for waste. The fast and automatic compressing device for the waste is high in waste compression speed. In order to achieve the aim, the fast and automatic compressing device for the waste comprises a first support, a sliding rail, a fixed seat, an electric push rod, a wedge-shaped block, a contact wheel, a fixed check block, a first spring, a second support, a second support, a lifting rod, a guide plate, a first pressing plate, a collecting frame, a containing table and a second pressing plate; the collecting frame and the first support are arranged at the top of the containing table, the collecting frame is located at the left side of the first support, the sliding rail is arranged in the middle of the top in the first support, the sliding block is arranged on the sliding rail, the wedge-shaped block is arranged at the lower end of the sliding block, and the second support is arranged in the middle of the left end of the wedge-shaped block. The fast and automatic compressing device achieves the advantages of being high in compressing speed and saving time and labor during work.