The invention discloses a special catalyst for preparing isophthalonitrile by ammoxidation of m-xylene. The carrier is silica gel, the main catalyst is three components of V, Mo and Sb, and the co-catalyst is at least one of D and E components. species; its active components are expressed as: VMo b Sb c D. d E. e o x ; The D is boron, chromium, titanium, phosphorus, nickel, bismuth, manganese, iron, cobalt, copper, zinc or tin; E is potassium, lithium, sodium, cesium, magnesium or calcium. The invention also discloses the preparation method and application of the catalyst. In the present invention, groups containing lone electron pairs on silicon are used to carry out Lewis acid-base reaction with inorganic elements, thereby strengthening the effect of inorganic oxides and supports; at the same time, the dispersion of inorganic oxides is more uniform, the loss of catalyst components is small, and the catalytic activity is high. , good selectivity, prolonging the service life of industrial catalysts from one year to more than two years. The preparation method of the catalyst is simple, the thermal stability and mechanical strength are good, and the catalyst can be used in fixed-bed and fluidized-bed reactors.