Abstract: An active-passive differential series-parallel connection supporting leg, a gravity-based closing series-parallel connection supporting leg, and a six-degree-of-freedom position-adjusting robot platform are provided. The six-degree-of-freedom position-adjusting robot platform is formed of a plurality of legs distributed in parallel, and includes a frame, a distributed controller, and multi-chain parallel legs, wherein a plurality of legs are fixedly connected with the frame through a base. The present disclosure integrates an omnidirectional movement and position adjustment to solve problems that the existing position-adjusting platform is fixed or moved inflexibly, the structure is over complicated, the occupation space is excessive, and the movement error is large, and thereby effectively expanding application range of the six-degree-of-freedom position-adjusting robot platform.