Based on cooperative knowledge management system, the necessity of green design was analyzed, and the characteristic of cooperative products green design was researched. After analyzing the system workflow of cooperative products green design, the shortest path decision-making model to support cooperative product green design evaluation based on ant colony optimization (ACO) approach was presented. Furthermore, the ACO approach was improved by Bayes theory. The Bayes decision can adjust the transfer probability of the ACO, and it can compress the search space effectively, improve the search speed, so that it can prevent the stagnation effectively. As a result, the better contraction results can be obtained.