The invention relates to a downhole tool capable of reducing drilling friction during sliding directional construction. The downhole tool comprises an upper joint, an upper outer cylinder, an upper mandrel, a lower joint, a lower outer cylinder and a lower mandrel. The upper joint is fixedly connected with the upper outer cylinder. The lower joint is connected with the lower mandrel. The upper outer cylinder is fixedly connected with the lower mandrel. The upper mandrel is located into the upper outer cylinder. The lower mandrel is located into the lower outer cylinder. An upper limiting block is arranged on eth upper mandrel. A lower limiting block is arranged on the lower mandrel. The upper limiting block is connected with a first spring. The lower limiting block is connected with a second spring.The downhole tool capable of reducing drilling friction during sliding directional construction has following beneficial effects: the downhole tool is of an all mechanical structure and can be switched between the 'off' state and the 'on' state; in the 'on' state, torque and drilling pressure can be transferred to a lower drilling rig without affecting drilling construction; in the 'off' state, an upper pipe column can freely rotate so that sliding friction can be significantly decreased and sliding directional drilling of the drilling rig below the tool is not affected; and by utilizing the tool, cost of drilling construction can be greatly reduced compared with conventional high-end technology including rotary steering.