Net hydrodynamic uplifting force of reversed tainter value in flat-bottom galleries of high-head lock was studied through steady flow tests,main result as follows:1）The pressure decreased on hemline is the main reason that increase net hydrodynamic uplifting force;2）The net hydrodynamic uplifting force of reversed tainter value has linear relation with square of Froude number of orifice current in every opening;3）The thickness change of value has little influence on the maximum net hydrodynamic uplifting force.