Abstract: According to the needs of module division for crowdsourcing design tasks under social product development and aiming at the ambiguity of the correlation among product atomic design tasks, the elementary theory and methods that an 11-level scale weighted networks was used to describe their relationships, and then the weighted network was pruned. An optimization model of module division of crowdsourcing tasks under social design was established with the objective function of maximizing the degree of aggregation within the module, and minimizing the coupling degree between modules, and minimizing the difficulty of collaborative design, and an ant colony algorithm was used to solve it. The calculation methods of relevance of functional and structural information exchange among atomic design tasks and of the difficulty of contractor cooperation were discussed. The principles and steps of crowdsourcing task module division were given. Examples were given to illustrate the feasibility of the proposed method.