In this paper a method of calculating the inverse and direct dynamic model of cooperative manipulators handling flexible objects is presented. In order to solve the dynamics of this system, the closed chain is divided into two subsystems, one is flexible, representing the object and the other is rigid, representing the tree structure of the two manipulators. The two subsystems are connected by calculating the wrench transmitted by the end effectors. An analytic solution is obtained for the dynamic model. The proposed solution leads to a classification of objects grasped by multiple manipulators.