Abstract: The theory is based on the complex hydromagnetic equations of nebula,which are simplified approximately to the equations of velocity.It is a solvable simple model.Then by using the qualitative analysis theory of nonlinear equation,a nonlinear dynamical mechanism of formation of binary stars is obtained.Under certain conditions some singular points in the two dimensional state correspond to the binary stars.Under other conditions the singular point corresponds to a single star.Therefore,the formations of various stars are evolutionary results from nebula.