In order to realize visualization and intelligence of computer-aided process planning, this paper proposes an intelligent system with the integration of workflow technology and max-min ant system. Workflow modeling technology was applied to represent multi-process routes decision-making problem (MRDP) and a heuristic algorithm based on expert knowledge was designed to construct the directed graph for MRDP. Moreover, a modified ant colony algorithm was proposed to exploit the best solution using improved max-min pheromone strategy and the way of updating pheromone. Finally, an experiment example is illustrated to demonstrate the proposed methodology.