The use of lanthanum phosphate as a vanadium trap for preventing destruction of USY zeolite was studied. The effect of deposited vanadium on the hydrothermal destruction of zeolite was investigated by the solid-state NMR technique. LaPO4 species can inhibit the zeolite framework structure from being collapsed by vanadium after steaming treatment. The EPR results show the oxidation-reduction reaction in LaPO4 and V2O5 system and inhibition of zeolite destruction by V5+. The catalysts prepared from USY and LaPO-USY zeolites were also tested in the catalytic reactions of heavy oil. The assessment results indicated that the USY modified with LaPO4 could bring about remarkably high dehydrogenation ability.