Abstract: Some factors affecting melt strength of PE100 tubing resin were analyzed such as temperature, extrusion rate, tensile length, tensile acceleration, distance of take-off-wheel pair. The significance of influencing factors on melt strength of PE100 tubing resin was studies by orthogonal experiment. The results showed that the main factors were the temperature and the distance in measuring wheel pair, the secondary cause was the tensile acceleration. The optimum conditions were A1(205 ℃), B1(0.1 mm/s), C3(102 mm), D3(24 mm/s2), E1(0.3 mm).