The invention discloses a gate mechanism. The gate mechanism comprises a gate, a driver, a movable seat, a first intermediate transmission assembly and a second intermediate transmission assembly, thedriver is provided with a first output shaft and a second output shaft, each of the first intermediate transmission assembly and the second intermediate transmission assembly comprises a driving wheel, a driven wheel and a transmission part, the driving wheel of the first intermediate transmission assembly is connected with the first output shaft, the driving wheel of the second intermediate transmission assembly is connected with the second output shaft, the transmission parts are wound around the driving wheels and the driven wheels, the first end of the movable seat is connected with the transmission part of the first intermediate transmission assembly, the second end of the movable seat is connected with the transmission part of the second intermediate transmission assembly, the gateis connected with the movable seat, and the driver drives the movable seat and the gate to move together through the first intermediate transmission assembly and the second intermediate transmission assembly so as to enable the gate to selectively open and close a throwing and putting port. According to the gate mechanism, the gate can be smoothly and steadily driven to open and close the throwingand placing port, and the advantages of being simple in structure and capable of effectively reducing noise are further achieved.