The characteristics of magnetostatic forward volume waves (MSFVWs) propagating in magneto-optical (MO) film waveguide under inclined bias magnetic field are analyaed. The dependences of MSFVW propagation constant and dynamic magnetization related to the MO coupling coefficients on mode number, frequency and inclined bias magnetic field are calculated in detail. It is shown that the greater the MSFVW frequency f and the mode number m as well as the less bias magnetic field Hi and inclination θ, the greater MSFVW propagation constant Ks is; the amplitude of zero-mode MSFVWs is much greater than that of high-mode MSFVWs. In an appropriate frequency range, MSFVW amplitude can be increased under an inclined bias magnetic field, and then the diffraction efficiency of guided optical waves with MSFVWs is improved.