The axial flow and grout type turbine seal adopts a doublelayer flat plate type sealing structure, which existed drawbacks of unstable operation, pressure fluctuation, flat wear, and other problems. A new method of increasing the lower plate in the lower sealing flat plate was put forward to improve the problem of flat side partial grinding and pressure fluctuation. By increasing the lower plate, the damage to sealing surface caused by tilting of lower flat plate edge is prevented, the surface friction between lower flat plate and antiwear ring is produced which avoid the local friction of the lower flat plate, and the pressure fluctuation caused by repeatedly tilting and falling of lower flat plate edge is prevented. The good effect was achieved for this sealing structure in practical application on site.