The invention discloses a double-component modification method of a molecular sieve in an FCC catalyst. The modification method comprises the following steps that 1, the molecular sieve is added intoa phosphorus-containing aqueous solution, wherein the mass ratio of the phosphorus-containing aqueous solution to the molecular sieve is (2-5):1; the pH value is adjusted to be 1-10, a stirring reaction is carried out at 70-200 DEG C, then flash drying is carried out, and a filter cake is roasted for 0.5-6 hours at 180-650 DEG C by using 0-100% water vapor to obtain a phosphorus modified molecularsieve; 2, the phosphorus modified molecular sieve is added into a transition metal aqueous solution, wherein the mass ratio of the transition metal aqueous solution to the molecular sieve is (2-10):1; a stirring reaction is carried out at the temperature of 0-100 DEG C, then flash drying and roasting are carried out, and a double-component modified molecular sieve is obtained, wherein the concentration of the phosphorus-containing aqueous solution is 0.1-1 mol/L, and the concentration of the metal iron aqueous solution is 0.01-0.1 mol/L. The method can prevent the great loss of the phosphoruscomponent of the phosphorus modified molecular sieve in transition metal exchange modification, and the acid amount of molecular sieve strong acid is improved.