The generation and manipulation of terahertz wave is crucial for the advancement of terahertz technology. The designable geometry and specific resonance response of metamaterials offer a novel approach for generating and manipulating terahertz waves. However, the low conversion efficiency of terahertz wave from metamaterials remains a challenging issue to be addressed. In this paper, a metamaterial was designed which consisted of metal resonator ring array and all-dielectric silicon split ring resonators. The terahertz wave radiation and manipulation of the metamaterial were studied by using self-consistent equations consisting of Maxwell's equation and the hydrodynamic model of the electron motion. It was discovered that by optimizing the opening direction of the split ring resonators, the amplitude of terahertz waves generated by the metamaterial was doubled. Furthermore, control over the amplitude of terahertz wave was achieved by altering both the polarization angle of incident light and the geometry of the metamaterial. This work opens up new possibilities for compact and tunable terahertz sources based on metamaterials.