Catalytic cracking method and device capable of increasing propylene yield and improving properties of gasoline

The invention provides a catalytic cracking method and a catalytic cracking device capable of increasing propylene yield and improving properties of gasoline. The method comprises: (1) introducing a heavy oil raw material into the first reaction area of a riser reactor and mixing and contacting the heavy oil raw material with a regenerant to perform an reaction under a catalytic cracking condition; and (2) allowing light hydrocarbon raw materials to enter a bed reactor from the bottom and contact with another path of regenerant entering the bed reactor from the top in countercurrent for reaction, wherein after reaction, the catalyst is striped and delivered to the second reaction area of the riser reactor to mix, contact the catalyst with the oil gas and catalyst in a riser for reaction; and after reaction, the oil gas and catalyst are separated, the separated catalyst is stripped, regenerated and recycled, and the separated reaction oil gas is further separated to give products such as liquefied gas, gasoline and diesel oil. The method provided by the invention can improve low-carbon olefin yield of a catalytic cracking device, convert butene and benzene into propylene and ethylene, avoid influencing the adoption of other heavy raw materials by the device and obviously improve the properties of the gasoline.