In this work, the influence of the magnetoelastic field on the magnetic properties of FeCo thin film is analyzed by the micromagnetic model. Formula of magnetoelastic energy related to the stress between the FeCo and the underlayer are derived to analysis the role of stress on soft magnetic properties. The cubic anisotropy determines the symmetry of the loops. For the magnetoelastic field, the main term Hma has significant influence on the easy-axis coercivity and the cross term Hmb affects the slope of the hard-axis loop. Good in-plane anisotropy of FeCo thin film, which can be obtained by using certain underlayers (such as Cu, NiFe, CoFe), is corresponding to low value of Hma and Hmb. The magnetization 4πMs at amorphous grain boundary has great effect on the properties of FeCo film.