Floor thickness gauge

The invention provides a floor thickness gauge comprising a cylinder housing. A dial gauge is arranged at the outer side surface of the cylinder housing; and an anti-self-locking structure is arrangedin the cylinder housing. A switch includes a switch protrusion perpendicular to a connecting rod. A notch in which the switch protrusion can be inserted is formed in the cylinder housing; and the switch protrusion can move up and down in the notch. A connection dowel steel is arranged below the anti-self-locking structure. A spring is arranged between a second support plate and a second support body; a second support rod is hinged to a small dowel steel and an external extending rod successively and downwardly; and the end portion of the small dowel steel is hinged to the middle part of the external extending rod. A tightening ring sleeves the outside of the cylinder housing; and a pointer is arranged at the tightening ring and is arranged on the surface of the dial gauge. The floor thickness gauge based on a sim