Abstract: Oily sludge (OS) is a complex multi-phase mixture generated during oil and gas drilling processes and is classified as hazardous waste that requires effective treatment to ensure the safety of the ecological environment and enable resource recycling. Conventional OS treatment technologies, such as incineration, pyrolysis, and co-processing in cement kilns, have been employed for achieving OS separation and resource recovery. However, these technologies usually suffer from drawbacks in terms of disposal efficiency, the degree of resource utilization, and technical economics. With the global push for "carbon neutrality", there is a growing demand for the effective and energy-efficient treatment, resource utilization, and secondary pollution control of OS. Consequently, there is an urgent need for the development of novel highly efficient treatment technologies for accomplishing the effective and low-energy consumption remediation of OS and efficient recovery of its oil resources. This paper discussed the classification, hazards, and physicochemical properties of OS, followed by an overview of current mainstream OS treatment technologies. A comprehensive comparison of the advantages and disadvantages of each treatment method was provided, and the emerging low-temperature cyclone separation technology for OS separation was discussed. Finally, the future development trends in OS treatment technology were further discussed, aiming to promote the green and sustainable development of the petroleum and petrochemical industry.