A modal control optimization method for adaptive optics on the tempo-spatial domain is presented. The spatial modes of the adaptive optics system can be obtained by the singular value decomposition of the response function matrix of the adaptive optics system. The number of correction modes is determined dynamically by the root mean square estimation of the residual aberration after the correction with different number of modes. A Smith compensator is designed to reduce the time delay effect on the closed-loop system. The modal optimization method is experimentally verified by compensating phase distortion produced by artificial atmospheric turbulence in laboratory. Experimental results show that the correction capability of the adaptive optics system can be greatly improved in comparison to that of the generic modal gain integrator approach with the fixed number of correction modes. The modal control optimization method is an attractive and practical alternative to adaptive optics control.