On- the- spot experiments of different kinds of gathering- fish lamps were carried out in the fisheries studies of the Symlectoteuthis oualaniensis fishing ground in the north-west of Indian Ocean in October 2003. According to the dimension of the ship and the products, the illumination distribution of gathering- fish lamp and the fishing efficiency were studied. When the output of metal halide lamps is 240 kW, in the above 5 m water layer the illuminations are more than 100 lx , the iso- illumination curve of 10 lx is in the depth of 20 m, the iso- illuminance curve of 0. 01 lx is in the depth of 55 m. When the output of high pressure sodium lamps is 10 kW, the average illumination on the sea surface is 3 lx, the iso- illuminance curve of 0. 01 lx is in the depth of 20 m. According to the suitable illumination from 0. 01 lx to 10 lx of some squids, the ratio of water volume of high pressure sodium lamps and gathering- fish lamps is 1..5. When using high pressure sodium lamps, the density of squid w ill increase, the fishing layer will be shallower , the fishing efficiency will be higher, and the average product will be 3 times as much as before. It also shows that the total power output of the large squid jigging boat should be 112 to 160 kW in fishing Symlectoteuthis oualaniensis, and the suitable illumination for Symlectoteuthis oualaniensis is about 0. 01 lx .