The linear spin-wave spectra in Fe-Ni polycrystalline films and YIG single crystal films have been observed. It is found that in the spin-wave spectrum of magnetic film the odd and even modes are usually excited simultaneously, and their intensities change in accordance with different envolopes. Further investigations indicate that the positions and relative intensities of the odd and even modes vary with the depositing process and annealing of the film. All these experimental results can be well explained in terms of the Surface-Volume Inhomogeneity (S-VI) Model and the Asymmetric Volume Inhomogeneity (AVI) Model. In this paper the equipment and the relevant methods for measuring the spinwave spectrum are also described briefly.