The invention provides an innocent treating and recovering method and device of sump oil in an oil field, relating to a sump oil recovering process in the field of petroleum industry. The innocent treating and recovering method comprises the steps: oxydative degradation, settling separation, water-washing, demulsification and dehydrating, and the like. The innocent treating and recovering device comprises a sump oil oxidization pond, a sump oil settling pond, a heating furnace, a sump oil washing tank and a thermo-chemical dehydration device. By combining and utilizing a conventional treating process and equipment conditions of the oil filed, the innocent treating and recovering method and device provided by the invention have the remarkable advantages distinctive from other process technologies, and are low in investment and strong in realizability; the whole process is not impacted by a load, parameters of the unit treating process can be freely adjusted according to the specific requirement of oil-containing sludge treatment, thus the treating process has a certain adaptive capacity; the innocent treating and recovering method is simple in process, convenient to operate and manage and low in daily operation cost; the innocent treating and recovering device is stable in operation, recovered crude oil and treated solid phase impurities are stable and reach the standard; and the innocent treating and recovering device is controlled by adopting an automatic and manual combining manner, and brings the convenience for continuous large-scale production.