Dosidicus gigas is one of important fishing targets in the Chinese squidigging fishery which is distributed in the high seas off Chile. Effective utilization of fishattracting light power is an important aspect of fishing techniques. In the paper, light attenuation coefficient is estimated based on the in suit measurement of light intensity in the squid fishing ground off the coast of Chile. Meanwhile, the calculation model of underwater light illumination is established theoretically, and the “Xinshji No.52” squid fishing vessels is considered as an example to analyses effective utilization of fishattracting light power. The results show that the light attenuation coefficient of metal halide lights equals to 0.2 in the water. With the lights moving up, the suitable illumination volume between 0.1 and 10 lx (called the “effective v olume”) increases continuously, but the increasing ratio displays a downward trend, it is appropriate for the vessel to set the height of lights at 6.5 m. Effective volume can be maximized by setting lights distance at 0.55 m, therefore, it is proposed that lights distance increase from 0.5 m to 0.55 m in the vessel. Effective volume increases with total power of fish attracting lights, and reaches the maximum at total power of 300 kW. It is recommended that the total power of the vessel reduce from 360 kW to 300 kW. The setting and requirements of fishattracting light can be modified according to fishing area and fishing target. It is not advisable to put more and more power on fishattracting light.