Insulating oil filtering system and filtering method

The invention discloses an insulating oil filtering system and a filtering method, which are used for solving the problem that the existing insulating oil filtering system is manually operated and is low in automation degree. The insulating oil filtering system comprises an oil filter, N first oil tank assemblies, a second oil tank assembly and a control device. A first oil tank in each first oil tank assembly is communicated with a first oil inlet and a first oil outlet of the oil filter through a first valve and a second valve respectively; a second oil tank in the second oil tank assembly is respectively communicated with a first oil inlet and a first oil outlet of the oil filter through a third valve and a fourth valve; the first liquid level detection instrument and the second liquid level detection instrument are respectively arranged on the first oil tank and the second oil tank; the control device is used for controlling the corresponding valve to be opened and closed according to the detection result