SrFe12-x12-xCrxxO1919 (x=0—10) hexaferri te nanoparticles have been fabricated using a sol-gel technique for perpendicular magnetic recording. Experimental results have shown that the values of specific saturation mag netization, σss, increase for x≤04 as the Cr doping content incre ases, and reach maximum at x=02, while the coercivity, Hcc, decreas es for x＜05 This feature is favorable to magnetic recording. It is also fou nd that the α-Fe22O33 non-magnetic phase appears after x=06 and remai ns to be a hexagonal magnetoplumbite phase for x=0—04 Magnetic measurem ents have revealed that Cr substitution can decrease the magnetization and incre ase the peak-widening for Hopkinson peak when doped with Cr3+3+.