The operating condition of a cw simultaneous dual-wavelength Nd:YAG laser for both 4F3/2-4I9/2 (quasi-threelevel system) and 4F3/2-4I11/2 (four-level system) transitions is studied. According to this condition, the cw simultaneous dual-wavelength at 1.06μm and 946 nm in Nd:YAG crystal has been realized experimentally through an adaptive coating design of the cavity mirrors. A total power output of 2.5W of the dual-wavelength at 946nm and 1.06μm has been achieved with an optical conversion efficiency 14.3%. The experimental results are in good agreement with the theoretical analysis.