The invention discloses a bearing-platform-type narrow base tower for overhead double-circuit line cable T joint leading down. The bearing-platform-type narrow base tower comprises a tower body, a ground wire cross arm, an upper guide line cross arm, a middle guide line cross arm, a lower guide line cross arm, auxiliary cross arms, a V-shaped suspension string, a supporting insulator, a terminal bearing platform and a cable terminal. The ground wire cross arm is located at the top end of the tower body, and the upper guide line cross arm is located below the ground wire cross arm. The middle guide line cross arm is located below the upper guide line cross arm, and the lower guide line cross arm is located below the middle guide line cross arm. The two layers of auxiliary cross arms are located below the lower guide line cross arm, and the terminal bearing platform is located below the auxiliary cross arms. Two-side cross arms are arranged in the vertical line direction of the tower body. Cable T joint is achieved through the base tower, the construction cost is low, the occupation area is small, influences on stress of adjacent pole towers are small, and the original line arrangement mode is not changed; and adjacent tower transformation is not needed generally, the bearing-platform-type narrow base tower is suitable for construction of adjacent linear towers and strain towers,meanwhile the cable terminal is located on a platform of the tower body, and operation and maintenance overhauling is more facilitated.