F1-ATPase is a unique enzyme. The hydrolysis (or synthesis) of ATP into ADP and Pi produces an energy transformation from chemical energy to mechanical energy with exceptionally high efficiency. This energy transducing molecular motor is increasingly regarded as a key to the fundamental cellar motions and the nanobiotechnology. To fully understand the chemomechanical mechanism of the rotation of F1-ATPase, we propose a functional computation model based on some experimental results. We show that the torsional energy and stepwise rotation are regulated by a series of near-equilibrium reactions, with fitting parameters such as the rate constants, ATP concentration and the statistical steps, etc. The rotational characteristic, as demonstrated in experimental work done by others, may behave by the Michaelis-Menten kinetics.