Abstract: The author considered a class of struggle of existence in multigroup of nonlinear singular perturbation systems. Under appropriate conditions, the author constructed the external solution of the system, boundary layer correction terms and initial layer correction terms, and obtained the asymptotic expansion of the solution. The author discussed the existence of solution of the problem and the uniform validity of its asymptotic expansion.

Key words: nonlinear, multigroup, struggle of existence, singular perturbation