On the crack problem of ferromagnetic solids, almost all studies in previous literatures used two simple crack models, e.g., permeable and impermeable crack models. This means that a crack is always assumed to be a slit without thickness (mathematical crack). In fact, when a ferromagnetic solid with a crack is placed in magnetic fields, the mechanical/or magnetic loadings will make the crack opening and the high magnetic fields will be induced inside the deformed crack. Thus, the crack should be modeled as a semi-permeable cavity. In the present work, the semi-permeable crack model is adopted to study the fracture problems of a soft ferromagnetic solid. The general solutions are derived for complex potential functions and the intensity factors of fields. For some special cases, more explicit solutions are given and compared with those in literature. Numerical results are also presented to discuss the effects of magnetic fields inside the crack on fracture behavior of the ferromagnetic solid, and it is found that the model of semi-permeable crack is more reasonable than that of permeable crack or impermeable crack.