Abstract: Based on point source model of illumination on sea surface, we calculated the effective light distance and analyzed the optimal distance between light vessels in a chub mackerel purse seine fishing group, in which the total power of main light vessel, secondary light vessel, net vessel were respectively about 180 kW, 120 kW and 40 kW. The results show that when appropriate illumination being 0.01 lx, effective light distance is 872.0 m, minimum operating distance is 1 650.4 m between main light vessel and secondary vessel, 1 585.7 m between secondary light vessel and net vessel, and 1 669.7 m between main light vessel and net vessel. Optimal distance between two groups of purse seine vessels is 1 744.0 m. When appropriate illumination being 14.00 lx, effective light distance is 138.3 m, minimum operating distance is 262.9 m between main light vessel and secondary vessel, 249.4 m between secondary light vessel and net vessel, and 263.1 m between main light vessel and net vessel. Optimal distance between two groups of purse seine vessels is 276.6 m.