Abstract: The refining of poor quality and heavy crude oil leads to considerable by-products including high-sulfur petroleum coke and oily sludge, which pose potential threats to the ecological environment. Gasification of high carbon containing resources to useful syngas (CO+H₂) with near-zero pollution emission is a direct, economic and more environmentally. Friendly technology for refineries to utilize the oily sludge and petroleum coke in an integrated fashion. In order to prepare high performance oily sludge-coke slurry for commercial gasification technology, the slurry forming ability of oily sludge and petroleum coke with dry grinding and wet mixing processes were investigated, and the effects of particle size distribution, oily sludge additive amount, temperature and pH value on co-slurry ability were analyzed. The characterization results show that the petroleum coke had strong hydrophobicity, undeveloped pore structure and small specific surface area. The optimum mass-ratio of petroleum coke coarse to fine particles was 5.5∶4.5. When the slurry was prepared by oily sludge and petroleum coke, the optimum addition of oily sludge was 3.0%, the temperature was 30℃ and the pH was from 7-9. At the optimum conditions, mixed slurry with better liquidity, whose viscosity was less than 1000mPa·s and with a stable time more than 48h, could be obtained.