The invention discloses a well flushing sealing device, and belongs to the field of petroleum. The well flushing sealing device comprises an upper connector. A core shaft is connected with the inner side of the lower end of the upper connector. A wedge-shaped body is connected with the outer side of the upper end of the core shaft. The outer side of the upper end of the wedge-shaped body is sleeved with an anti-resistance soft ring. A slide sleeve is connected between the lower end of the anti-resistance soft ring and the outer side of the upper end of the wedge-shaped body. A lower connectoris connected with the outer side of the lower end of the wedge-shaped body. A ball seat is connected with the inner side of the middle of the lower connector and the inner side of the lower end of thewedge-shaped body. A ball is connected with the inner side of the upper end of the ball seat. A plurality of core shaft hooks are arranged on the outer side of the upper end of the middle of the coreshaft. The outer end of the middle of the wedge-shaped body is an inclined face. A plurality of hook grooves which are through are formed in the upper end of the middle of the wedge-shaped body. A plurality of slide sleeve inner grooves matched with the core shaft hooks are formed in the lower end of the slide sleeve. The lower end of the core shaft is connected with the lower end of the wedge-shaped body through an unsealing shear pin. Through the cooperation of the core shaft hooks and the slide sleeve inner grooves and through the ball on the ball seat, well flushing liquid can be prevented from entering a stratum.