A cleaning fluid circulating, separating and recharging system used in the process of refining light diesel oil from waste engine oil comprises a cleaning fluid circulating pipeline, a spray cleaning device, a cooling liquefaction device and an oil-gas separator, wherein the spray cleaning device is arranged on the cooling liquefaction device; the upper part of the spray cleaning device is connected with the cleaning fluid circulating pipeline and a pipeline used for conveying gaseous diesel oil; the lower part of the cooling liquefaction device is connected with the oil-gas separator; an oil-cleaning liquid separating tank is arranged under the oil-gas separator, and comprises a tank body, a mixture inlet pipe, an oil outlet pipe, a cleaning fluid outlet pipe, and cleaning fluid remaining in the tank body; the mixture inlet pipe, the oil outlet pipe and the cleaning fluid outlet pipe are arranged on the tank body and communicated with the oil-gas separator; the cleaning fluid outlet pipe is arranged at the lower part of the tank body, and is communicated with the cleaning fluid circulating pipeline; a circulating pump is arranged on the cleaning fluid circulating pipeline; a recharging pipeline is connected onto the cleaning fluid circulating pipeline in parallel. The cleaning fluid circulating, separating and recharging system has the advantages that the mixture of oil and the cleaning fluid can be separated; the cleaning fluid can be recharged regularly to ensure that the quantity of the cleaning fluid in the circulating process is relatively stable.