The wave equation for nonlinear magnctostatic surface waves (MSSW) on ferromagnetic film is derived with perturbation theory under the condition of transverse magnetisation, and its solution is found. The nonlinear dispersion relation shows that a high wave power results in a reduction of frequency band of MSSW. The variations of group velocity dispersion and nonlinear frequency shift with the wave frequency and film thickness are also studied. The results show that the bright pulse envelope solitons can not exist in our case.