Abstract: With the aid of the stochastic averaging method,the theory of singular points of diffusion processes and the method of invariant measure, a Hopf bifurcation system in the presence of parametric real noises is studied. It is found that in this nonlinear stochastic system, due tothe presence of the parametric real noises, a change of the type of bifurcation takes place and two bifurcation points appear, which differ from the original Hopf bifurcation one.

Key words: real noise, parametric excitation, stochastic averaging method, diffusion process, singular boundary, invariant measure, stochastic bifurcation