Float type level gauge for high-temperature high-pressure or high-temperature low-density medium

The invention relates to a float type level gauge for high-temperature high-pressure or high-temperature low-density medium, comprising a float chamber, a float and a graduated scale; the float type level gauge is characterized in that: the float is a hollow spherical shape; the float type level gauge further comprises a guide rail and a magnetic connector, a magnetic steel or a disc-shaped magnetic steel is arranged in the magnetic connector and forms magnetic attraction with a magnetic ball body in the float made of the nonferrous magnetic material or the disc-shaped magnetic steel the float made of the nonferrous magnetic material, a metal shaft laterally spanned at two side walls of the magnetic connector is exposed to two side walls and is attached to the guide rail by magnetic force, and the metal shaft can move up and down along the guide rail under the driving of the magnetic force; in addition, resistance wires are wound on the guide rail to measure the change of the resistance value of a return circ