The invention discloses a method and a system for catalytic conversion of poor quality raw material oil. The method comprises: feeding poor quality raw material oil into a riser reactor, carrying outa catalytic conversion reaction, feeding the obtained reaction product into a product separation unit, separating, and carrying out aromatic hydrocarbon extraction on the obtained diesel oil, whereinthe partial regeneration catalyst is added to the second diameter expanding section after the partial semi-spent catalyst is taken out from the first diameter expanding section at the middle portion of the riser reactor. According to the present invention, with the method and the system, the poor quality raw material oil is converted into high octane number gasoline and propylene while the yieldsof dry gas and coke are greatly reduced so as to achieve the efficient utilization of petroleum resources.