Abstract: The issue of the filling body exhibiting a certain degree of subsidence and self−flow slope angle following paste filling, which results in a suboptimal filling effect, must be addressed. In order to enhance the filling and roof−contacting efficacy of narrow and long downward drift stope and circumvent the instability associated with an excessively large exposed area of roof, a floating box−type point pillar roof−contacting technology was proposed. The bearing mechanism of floating box−type point columns was analyzed, and the calculation methods of floating box size, strength, and spacing were quantified. A series of field experiments were conducted to ascertain whether the floating box could float in a high viscosity slurry. The efficacy of the proposed design method and roof connection technology was validated through a case study of their application in a lead−zinc mine in Yunnan. The results demonstrated that the floating box can float in the high viscosity slurry and partially protrudes the filling body, thereby providing an effective support for the roof. The pressure exerted by the roof of the test stope on the floating box of the filling body was approximately 0.6 MPa. The utilization of floating box−type point−column roof−contacting technology enabled the formation of a joint support system comprising the filling body and floating box−type point−column. This configuration enhanced the stability of the roof, offering substantial safety benefits.