Magnetostrictive materials with high magnetomechanical coupling performance are required for transducer design and tunable resonator applications. The magnetostriction of Fe-Ga and Co-Fe alloy can be remarkably increased by high-density and semicoherent nanoparticles. In this work, we found that the magnetomechanical coupling of Co70Fe30 alloy can be obviously enhanced by high-density nanoprecipitation. This outstanding enhancement originates from the semicoherent face-centered tetragonal (fct) nanoparticles embedded in a body-centered cubic (bcc) matrix, which may promote magnetic domain rotations under applications of stress. The result indicates that high-density nanoprecipitation can be used to guide the design of magnetostrictive materials with unusual magnetomechanical coupling performance.