The invention discloses a modular constant-temperature multi-filter cylinder oil mist purifying and deslagging filtration system, comprising an integrated dirty oil collection unit, two or more dirty oil filter units capable of simultaneously and / or alternately running, a backwash mechanism for backwashing filter elements in the dirty oil filter units by turns, a sludge filter unit for carrying out secondary filter on the sludge discharged from the dirty oil filter units, a temperature control unit for cooling and / or heating the clean oil output from the dirty oil filter units and sludge filter unit, and an oil tank for collecting the clean oil processed by the temperature control unit, and the like. The invention has the advantages of compact structure, small volume, easy assembly and maintenance, and low cost, can realize thermostatic control of the temperature of the cutting fluid, guarantees the processing precision, avoids the problems of back flow due to accumulation of dirty oil, oil temperature variation and the like in the backwashing process of the filter devices, can discharge slag conveniently and rapidly, can effectively realize the recycling of resource, energy conservation and environmental protection, and can increase the additional value of the products.