In this paper, domain decomposition method (DDM) for numerical solutions of mathematical physics equations is improved into dynamic domain decomposition method (DDDM). The main feature of the DDDM is that the number, shape and volume of the sub-domains are all flexibly changeable during the iterations, so it suits well to be implemented on a reconfigurable parallel computing system. Convergence analysis of the DDDM is given, while an application approach to a weak nonlinear elliptic boundary value problem and a numerical experiment are discussed.