The existing filling hydraulic supports were generally designed by increasing the safety factor of the each structure of the support, thus resulting in a large overall weight of the hydraulic support, high cost, and low efficiency in the operation of the underground support. By establishing the force model when the hydraulic support was working, the stress of the main components of the hydraulic support during operation was analyzed, and the kinematics was studied. The results showed that the load acting on the front and rear pillars of the filling hydraulic support was more than 4 times of the load acting on the middle pillar, which provided a theoretical basis for optimizing the structure of the hydraulic support and improving the reliability of the hydraulic support.