Catalytic conversion method for hydrocarbon oil

The invention discloses a catalytic conversion method for hydrocarbon oil. The method comprises the following steps of: introducing a preheated heavy hydrocarbon oil raw material into a first lifting pipe reactor from a bottom; undergoing a contact reaction with a catalyst, making a reaction product flow upwards; introducing reaction oil gas and a spent catalyst into an oil-agent separating system from an upper outlet for separating; stripping the separated spent catalyst, regenerating and returning to the reactor for recycling; introducing separated reaction oil gas into a main fractionating tower; extracting a part of circulating oil on the top of the main fractionating tower, and introducing into a second lifting pipe for freshening; and mixing reaction oil gas separated from the outlet of a second lifting pipe reactor with reaction oil gas of the first lifting pipe reactor, and entering a subsequent separating system for further separating to obtain a product. Due to the adoption of the method provided by the invention, the yield of petroleum can be increased by 3-10 percent, the yield of liquefied gas is increased by 0.5-3 percent, the olefin content of petroleum is lowered by 5-20 percent, the RON (Research Octane Number) of petroleum is increased by 0.2-2 units, and the yield of low-quality catalyzed diesel oil is lowered.