The invention relates to a cutting device of a tire section and belongs to the field of production equipment of tires. The cutting device of the tire section is provided with a saw body. The cutting device of the tire section is characterized in that the saw body is clamped on the rear side portion of a saw belt through clamping pieces; an inner axial bearing and an outer axial bearing are respectively arranged on the internal and external of the saw body; and the inner axial bearing and the outer axial bearing are contacted with the rear portion of the saw body. The cutting device of the tire section has the advantages of effectively protecting the saw belt, achieving the improvement of the service life of the saw belt and achieving the purpose of reducing cost allowance due to the facts that the inner axial bearing and the outer axial bearing bear the friction force of the rear side of the saw belt, the saw belt is rubbed with the bearings in the advance process of the cutting, and the rotation of the bearings reduces the sliding friction of the saw belt.