The invention relates to an anti-scale soft seal flat gate valve. The anti-scale soft seal flat gate valve comprises a valve body, a valve deck arranged on the upper portion of the valve body, a manipulator arranged on a support of the upper portion of the valve deck and a valve clack connected with the manipulator through a valve shaft. The valve clack is of a flat plate structure and is sealed unilaterally. The forward pressure bearing side, aligned with an inlet of a flow channel, of the valve clack is of a frame structure, and the reverse pressure bearing side, facing an outlet of the flowchannel, of the valve clack is a plane. The reverse pressure bearing side is provided with a serrated groove for embedment of a serrated sealing ring. The valve deck is internally provided with a guide slot for opening and closing the valve clack. Compared with the prior art, the anti-scale soft seal flat gate valve has the advantages of being small in thickness, small in installation space, highin water testing qualified rate, capable of achieving the bidirectional pressure bearing function, low in cost, short in machining period and the like.