The effect of the CrRu–SiOx underlayer with different doping concentrations and the thickness of the CrRu underlayer on the microstructure and magnetic properties of FePt–C films were investigated. FePt films exhibited L10 (001) texture at various SiOx doping concentrations. The coercivities were as large as 28 kOe and the slope of M–H loop at coercivity was approximately equal to 1, suggesting that FePt grains were well exchange decoupled. Grain size was only slightly reduced after introducing the CrRu–SiOx underlayer. But the contact angle between the FePt grains and the MgO intermediate layer around 135° indicated the a MgO intermediate layer was not favored for smaller grains to obtain good L10 (001) texture. X-ray photoelectron spectroscopy in-depth profile showed that Si diffused into a whole FePt–C layer and C diffused to the film surface.