The invention provides a high precision tongue tube fuel sensor, which comprises a tongue tube theostat and a floater; wherein, the floater is arranged in the tongue tube theostat and comprises a hollow floater shell and a magnetic steel embedded in the interior of the floater shell; the floater is integrally sealed and the average density thereof is 70.8%-79.2% of fuel density. The high precision tongue tube fuel sensor has simple structure, high precision, accurate measurement of fuel change and reliable performance.