The invention discloses a diamond sintered grinding wheel bar and a manufacture method thereof. The diamond sintered grinding wheel bar comprises a bar body and a tubular abrasive particle layer. Thebar body comprises a main body and a connection end located at one end of the main body. The tubular abrasive particle layer comprises a fixed end and an edge part connected with the fixed end. The fixed end is arranged at the connection end in a sleeving manner and fixed to the connection end. The edge part is in a sleeve shape. The tubular abrasive particle layer is formed by mixing and sintering a metal binding agent, diamond abrasive particles, an additive and a water-based adhesion agent. By arranging the edge part of the tubular abrasive particle layer into a sleeve shape, the R angle abrasion upper limit of the side face of the end portion of the grinding wheel bar is limited, the R angle of the lateral side of the end face of the edge part is controlled within a reasonable range, and therefore the machining allowance reserved for finish machining is reduced, and the cost of finish machining is reduced; and chip removal and cooling during deep hole and groove machining are facilitated, the occurrence of the knife burning phenomenon is reduced to the maximum extent, the service life of the grinding wheel bar can be prolonged, and meanwhile the product yield is increased.