The Fex Pt 100x (10nm) (x=31–51) thin films are fabricated on Si (100) substrates by using magnetron sputtering. The highly ordered L1 0 FePt phase is obtained after post-annealing at 700℃in Fe 47 Pt 53 thin film. The sample shows good perpendicular anisotropy with a square loop and a linear loop in the out-of-plane and the in-plane direction, respectively. The variations of the magnetic domains are investigated in the films when the content value of Fe changes from 31% to 51%.