The invention discloses a process for treating an inferior oil product. The process comprises a hydropretreating reaction zone, a hydrotreating reaction zone and a catalytic cracking reaction zone. The process comprises the following contents: mixing a residual oil raw material and hydrogen, then successively allowing the mixture to pass through the hydropretreating reaction zone and the hydrotreating reaction zone which are connected in series, subjecting a reaction effluent of the hydrotreating reaction zone to gas-liquid separation, allowing a gas phase to recycle back to the hydropretreating reaction zone and/or the hydrotreating reaction zone, allowing a liquid phase to directly enter the catalytic cracking reaction zone and carrying out a catalytic cracking reaction, and separating a catalytic cracking reaction effluent so as to obtain dry gas, liquefied gas, catalytically cracked gasoline fraction, catalytically cracked diesel fraction, catalytically cracked heavy recycle oil and catalytically cracked slurry oil, wherein the catalytically cracked diesel oil, the catalytically cracked heavy recycle oil and the slurry oil are partially or completely recycled back to the hydrotreating reaction zone for a hydrotreating reaction. The method provided by the invention can prolong the cycle of stable operation of equipment.