The invention provides a combined method for separating fluid catalytic cracking slurry oil and preparing oil-series needle coke. C3-C5 light dydrocarbon cut fraction is adopted as extraction solvent for conducting sub-critical or super-critical extraction on fluid catalytic cracking slurry oil, solvent is recovered from an obtained extraction oil phase in a super-critical mode to prepare extraction components, the extraction components serve as raw materials for preparing middle phase asphalt, and the middle phase asphalt is prepared through retrogressive reaction and then subjected to delayed coking reaction to prepare high-quality oil-series needle coke. When the sulfur content of fluid catalytic cracking slurry oil is high, extraction light components can be subjected to hydrodesulfurization treatment first, hydrogenated oil is subjected to fractionation to collect hydrogenation tail oil, the hydrogenation tail oil serves as a raw material for preparing middle phase asphalt, and then the needle coke is prepared. By means of the method, by controlling the preparation of middle phase asphalt and the coking procedure of the needle coke to be independent of each other, industrial implementation is easier, and fluid catalytic cracking slurry oil can be sufficiently used and the high-quality needle coke material can be prepared.