The monofilament with 0.304mm of diameter was produced using a polybutylene succinate (PBS) resin, and a gill net was made by it. We investigated the impact of heat setting temperature on the mechanical properties, knot state and height of gill net. Heat treatment was carried out using the high pressure steam machine for 20 minutes at temperature of 55℃, 60℃, 70℃ and 75℃. Before heat treatment, the strength and elongation of PBS monofilament were estimated to be 48.1kg/mm2, 23.8% at unknot, 37.6kg/mm2, 18.8% at single knot, 26.6kg/mm2, 22.9% at double knot in dry condition, respectively. The strength and elongation of PBS monofilament with double knot were decreased as heat setting temperature increased, and the decreasing rate of strength was showed to be higher than that of elongation. It was not found any differences in strength and elongation of PBS monofilament yarn with double knot at the 65℃ and 70℃ of heat setting temperature by 5% significance of T-test, but there was a significant difference at the 70℃ and 75℃ of heat setting temperature. The net's height and length from leg to leg appeared no differences at the 70℃ and 75℃ of heat setting temperature. In results, it was investigated that the PBS monofilament gill net with the maximized physical properties could be manufactured at 70℃ of heat setting temperature using a high pressure steam machine for 20 minutes.