The invention provides a novel additive for improving tumbler strength of vanadium-titanium magnet sintered ore. The novel additive contains, by weight percentage, 10-30% of B2O3, 5-20% of NaCl, 3-9% of NaNO3 and 45-85% of CaCl2, and the addition amount is 0.04-0.06%. The additive is added in a manner that the additive is prepared into a solution, the solution is added to a sintering mixed material when mixing for the first time is conducted, and a sintering test is conducted. It is indicated through test results that the content of magnetite, the content of hematite and the content of perovskite in the sintered ore are decreased; the content of calcium ferrite, the content of dicalcium silicate and the content of vitreous substances are increased; the air hole rate of the sintered ore is reduced; the proportion of maculosus-granular structures which are poor in strength in an ore phase structure is reduced; the proportion of corrosion structures which are good in strength is increased; the ore phase structure becomes more uniform; and furthermore, compared with that of sintered ore with no additive added, tumbler strength is improved by 1.5-3.5%.