We demonstrate a highly powerful acousto-optically Q-switched Nd:YVO4 yellow laser at 589 nm by using a Np-cut KGW crystal and a phase-matching lithium triborate crystal to performance the intracavity stimulated Raman scattering and second-harmonic generation, respectively. We experimentally verify that the design of the separate cavity is superior to the conventional design of the shared cavity. By using the separate cavity, the optical-to-optical efficiency can be generally higher than 32% for the repetition rate within 200-500 kHz. The maximum output power at 589 nm can be up to 15.1 W at an incident pump power of 40 W and a repetition rate of 400 kHz.