The effects of Ru underlayer on crystallographic structure, microstructures, and magnetic properties of Co72Pt28 films were investigated. It was observed that Ru deposition pressure played a more important role in determining the crystallographic texture compared to Ru thickness. Ru had a preferred (0002) texture when deposited at low Ar pressure and induced perpendicular magnetic anisotropy for Co72Pt28. However, at high Ar pressure, Ru (1010) and Ru (1011) peaks appeared that changed the easy axes of magnetization of Co72Pt28 film from out-of-plane to in-plane directions. With increasing thickness of Ru top layer in the dual-layer structure of Ru underlayer, coercivities increased due to increased magnetic anisotropy and reduced intergranular magnetic interaction.