In order that the probabilistic logic reasoning under uncertainty can be used for 1arge scale knowledge-base，this paper presents a clustering-algorithm for decomposi-tion of probabilistic logic formula set based on the general consistence assigning algorithm for Drobabilistic logic and the experience of developing the knowledge-base in an practical expert system． It ensures that the united-model of Dantzig-Wolfe decomposition can be used for probabilistic logic reasoning on probabilistic logic knowledge-base with different background，provided the formula set hold certain hierarchical structure．Experiments show that the algorithm performs successfully on instances with dozens of variables and clauses．