The invention provides a deep water net cage. The deep water net cage comprises a cage body, a netting and an operating platform, wherein the cage body comprises multiple stand columns, a lower floating body connected to the bottoms of the stand columns as well as an upper support structure connected to the tops of the stand columns, a first inclined strut is arranged on the top surface of the upper support structure, and two ends of the first inclined strut are connected with the upper support structure; the netting comprises an annular side net and a bottom net arranged at the bottom of theside net, the top of the side net is fixed with the upper support structure, and the bottom of the side net is connected with the periphery of the bottom net; the operating platform is arranged on thefirst inclined strut and the upper support structure. According to the cage body of the deep water net cage, the lower floating body and the upper support structure are connected to the bottoms and the tops of the stand columns through the lower floating body and the upper support structure, the stability of a main structure of the cage body can be guaranteed through the lower floating body and the upper support structure, and higher strength of the deep water net cage is guaranteed. The first inclined strut can enhance the strength of the upper support structure.