The invention relates to a flow gauge which can be called as a hyperboloid balance flow gauge, comprising a pipeline member 01 and a pipe-in throttling member 02. The pipe-in throttling member 02 is mounted on an inner wall of the pipeline member 01; and a diversion surface 03 is a cambered surface comprising an arc surface and a hyperbolical surface. The hyperboloid balance flow gauge further comprises a left pressure tap 04 and a right pressure tap 05; a welding port 08 and a welding port 09 are arranged at both ends of the pipeline member 01 for connecting an outer pipeline in a welding way, or a left flange plate port 06 and a right flange plate port 07 are arranged for connecting the outer pipeline; and the pipe-in throttling member 02 is mounted in the pipeline member in a pipeline inlaying way or a welding way. The diversion surface 03 adopts a cambered surface, in particular to a hyperbolical surface, thereby greatly reducing loss of momentum generated by the traditional pore plate or conical surface and slant throttling flow gauge to the fluid collision and greatly reducing resistance of the flow gauge to fluid. Compared with the traditional pore plate flow gauge, the invention can prevent flow media in the pipeline from generating two-phase separation change during flow and greatly improves the measuring precision.