Free Viewpoint Television (FTV) is expected to be a next generation visual application. Ray-Space representation is the main approach to realizing FTV with complex scene. Data compression in ray-space is one of key technologies in ray-space based FTV systems. Previous methods of ray-space data coding only utilize intra-slice redundancies which is similar to still image coding techniques, resulting in low coding efficiency. In this paper, data compression in ray-space is investigated, features of ray-space slice are analyzed, and ray-space compression method is proposed based on intra-slice correlation, inter-slice correlation and prediction technique. Experimental results show that ray-space compression efficiency is further improved.