The utility model discloses a connecting base assembly of an oil filter. The connecting base assembly is characterized in that the connecting base assembly is composed of a connecting base, an oil passing bolt, a screw plug bushing, a first O-shaped ring and a second O-shaped ring. The connecting base assembly is mounted on an oil cooler, and the oil filter is arranged horizontally through the connecting base and the screw plug bushing. Reinforcing ribs are distributed on the connecting base, so that the structure is more reliable. The face connected with the oil cooler is a round face, so that arrangement forms are made more flexible. The cost is low, the arrangement form of the oil filter can be changed without changing the oil cooler, and the cost for casting the oil cooler by making a mold again is saved.