The utility model relates to a valve, in particular to a flat gate valve. The flat gate valve comprises a valve body, a gate plate, a valve rod, valve seats, a valve cover and a hand wheel. The upper end of the valve body is fixedly connected with the valve cover, the upper end of the gate plate is connected with the valve rod, and the upper end of the valve rod is connected with the hand wheel. Valve seats are arranged on the left side and the right side of the gate plate to be tightly attached the gate plate, and the valve seats are provided with springs, O-shaped rings, reinforced poly tetra fluoroethylene (RPTFE) insert rings and rubber seal rings. The springs and the O-shaped rings are arranged at the positions where the valve seats are attached to the valve body, and the RPTFE insert rings and the rubber seal rings are arranged at the positions where the valve seats are attached to the gate plate. The flat gate valve successfully achieves inlet low pressure seal and outlet high pressure seal, is small in specific pressure and long in service life, and ensures strong seal performance.