Magnetic properties of ferromagnetic/ferromagnetic/antiferromagnetic trilayers with stress anisotropy are investigated by using ferromagnetic resonance method.Acoustic mode and optical mode are observed.As applied magnetic field in the plane of film.in some regions,with increasing stress anisotropy field resonance fields of acoustic and optical modes shift to higher values.With increasing ferromagnetic film thickness, the shift of acoustic mode resonance field is different. Furthermore.the resonance field of optical mode is irrelative with intensity of stress anisotropy.