Different amounts of amorphous SiNx nonmagnetic material and magnetic Co50Pt50 alloy were cosputtered on the different thicknesses of Ag films at room temperature then annealed at different temperatures. When the thickness of Ag underlayer is 25 nm, the CoPt/Ag film has a minimum in-plane squareness (S||) which is about 0.35. The out-of-plane squareness (S⊥), out-of-plane coercivity (Hc⊥), and saturated magnetization (Ms) values of the CoPt/Ag (25 nm) film are about 0.95, 15 kOe, and 420 emu/cm3, respectively. From the microstructure analysis of CoPt-SiNx/Ag (25 nm) films with different volume percent of SiNx content, it is found that the average grain size of CoPt decreases from about 80 to 9 nm when the volume percent of SiNx is increased from 0% to 50%. The S⊥, Hc⊥, and Ms values of the (CoPt)50-(SiNx)50/Ag films are- about 0.5, 7.5 kOe, and 200 emu/cm3, respectively.