Experiments were carried out to study the extrusion characteristics of a vane extruder based on extensional flow. The effects of rotor speed and die pressure on output were studied and compared with a single screw extruder. The responses of melt pressure to rotor speed and die pressure were also studied in real timescale. Experimental results show that the die pressure has little effect on output, which is significantly different from that of single screw extruders. Oscillation pressure was introduced into the extrusion process by the dynamic convergent-divergent flow channel of the vane extruder. The oscillation frequency of melt pressure is four times of that of the rotor angular frequency. The die pressure has a little influence on the oscillation amplitude of melt pressure. The oscillation amplitude of melt pressure increases with the increase of rotor speed. The oscillation amplitude of melt pressure decreases along the extrusion direction.