The invention discloses a preparation method of a negative temperature coefficient bead thermistor. A pentabasic oxide thermistor powder material is prepared by using cobaltic oxide, trimanganese tetroxide, nickel oxide, iron trioxide and magnesium oxide as raw materials through a ball-milling method; a thermistor sizing agent is prepared by adopting an organic solvent; a glue dispenser is adoptedto carry out quantitative control on bead forming; after high-temperature sintering and welding of an outer lead, packaging is carried out by adopting an inorganic high-temperature adhesive and a test wire is welded so as to prepare the bead thermistor. The thermistor prepared by the preparation method is applicable to a high temperature; a material constant B25 DEG C/50DEG C is 3500K+/-5%; at atemperature of 0 DEG C, a resistance value is 45 kohm+/-10%; at a temperature of 900 DEG C, after high-temperature ageing is carried out for 200 h, a R0 DEG C resistance value change rate is smaller than +/-4%. The high-temperature thermistor prepared by the preparation method is stable in high-temperature performance, good in consistency, stable in ageing performance and applicable to temperaturemeasurement and control in the fields of aerospace and automobiles.