Groove milling is an important working procedure in plastic profiles manufacturing. Rational milling parameters have great effect on machining efficiency and quality. The milling characteristic of plastic profiles is investigated by cutting experiments in the present paper. The cutting forces increase with the feed speed increase. The vibration occurs easily in transverse cutting because of the low stiffness of the plastic profiles. When the feed speed is large, the workpiece material would produce softening and daubing phenomena appears subsequently on the workpiece surface which affects machining quality. It is therefore that the milling parameters are determined by the avoidance of cutting vibration as well as daubing effect at the same time.