The invention relates to a hydrocarbon catalytic conversion method of productive low-carbon olefin and light aromatic hydrocarbon. The method comprises steps as follows: a heavy hydrocarbon raw material and a cracking catalyst are contacted in a first reactor and have a catalytic cracking reaction, a first carbon deposit catalyst and a first reaction product are obtained through separation; a light hydrocarbon raw material is injected from the upstream part of a second reactor, a medium hydrocarbon raw material is injected from the middle of the second reactor, and the mixture has a catalytic cracking reaction; a reaction mixture produced in the second reactor is introduced to the third reactor and continuously has a reaction, and a second carbon deposit catalyst and a second reaction product are obtained through separation; the cracking catalyst adopts a cracking catalyst containing modified beta zeolite, and the modified beta zeolite adopts phosphorus and transition metal M modified beta zeolite. With adoption of the method, higher propylene yield and light aromatic hydrocarbon yield can be obtained.