A series of magnetic modes were observed in LPE YIG films magnetized in plane. These magnetic modes were excited by means of magnetostatic wave excitation and show characterisitics of equal spacing and slower attenuation than normal standing spin waves. Considering that the precession is elliptical and supposing there are inhomogenuity of magnetization in the film, we deduced relation between mode spacing and magnetic parameters of YIG. Comparing with experiments, an inhomogenuity of 2.6—5.8% were deduced for our LPE YIG films.