Abstract: Based on shortcomings of traditional manual cleaning for internal floating roof oil tank such as long construction period, high labor intensity, poor safety and low crude oil recovery rate, a mechanical cleaning technology for internal floating roof oil tank is developed. The mechanical cleaning system mainly consists of 6 parts such as pumping and circulating, oil-water separation and recovery, N2 injection, ventilation, high-pressure water jet and gas monitoring. The process principle is to clean the internal floating roof oil tank by using the injected water circulation heating technology, oil spill recovery technology and high-pressure water jet technology. Specific procedures of mechanical cleaning for the internal floating roof oil tank are described in detail. Compared with manual cleaning, the mechanical cleaning technology can reduce the construction period by half and construction personnel by one third and lower safety risks and labor intensity. The technology can provide a reference to the cleaning of internal floating roof oil product tanks.