The invention discloses a union attachment joint which comprises a T-shaped tee joint. The T-shaped tee joint comprises an inlet, a first outlet and a second outlet, the end portion of each of the first outlet and the second outlet is provided with a limit boss, each of the first outlet and the second outlet is sleeved with a union retaining ring, the inner side of each union retaining ring is provided with a grove capable of accommodating the corresponding limit boss, one end of each union retaining ring is connected with the corresponding limit boss, a union nut sleeves each union retaining ring, the bottom end of each union nut is connected with an elastic collar for a shaft, a stepped hole is arranged at the position of the inlet, a union packing is arranged on the stepped hole, each union retaining ring is cylindrical, the end of each retaining ring extends to form a circular boss which is connected with the corresponding limit boss, the end of each union nut extends inwards to form a clamping ring, and the end of each clamping ring is clamped on the end portion of the corresponding circular boss. The union attachment joint is connected through the nuts and can bear oil pressure as large as 20000psi (140MPa); the union attachment joint is convenient to connect by the aid of the union nuts, good in sealing performance and low in cost.