Abstract: Tank sludge is a dark and dense gelatinous material layer formed on the tank bottom during oil storage. Due to containing BTEX, phenols and other toxic substances, it cannot be directly discharged. However, it will accelerate corrosion to the tank bottom plate so as to reduce service life of the oil tank and have some negative impacts on the tank oil quality and effective volume. Characteristics, hazards, cleaning cycles and costs of the tank sludge are analyzed simply. Inductive analysis on the status and development trend for tank sludge treatments worldwide is conducted on cleaning technologies, cleaning processes, recycling treatment technologies and other aspects. The application and research status worldwide on manual cleaning, mechanical cleaning, robot cleaning and other aspects are introduced. Through comprehensive analysis, it is proposed that the tank sludge cleaning technology will develop towards closing, integration, systematization and intelligence and sludge treatment will develop towards facilitation, reduction, harmlessness and recycling.