The hyperstatic-legged platform is the physical prototype for optical mirror support control. However, the hyperstatic problem leads to uncertainty in leg loads and platform attitudes, and current control schemes suffer from attitude oscillations and poor load controllability. This paper presents a geometry-leveling and load-uniforming coupling control method (G&LCC). Simulation comparisons of G&LCC with the point-chasing and fuzzy-control methods validate its unique ability to synchronously control platform attitudes with leg loads. Moreover, experiments based on a six-elastic-legged elastic platform demonstrate that only one to two iterations are required to adjust the attitudes to within 0.02°, while all leg loads converge to within 7% of expectations.