Abstract: A two dimensional finite elemental model is developed to simulate and analyze the compaction of the composite laminates during the autoclave processing. The model is based on the effective stress principle and Darcys law. The resin pressure is chosen as the additional degree of freedom of the nodes. The coupled equations are solved by the backward difference and direct approach because of its rapid convergence. The results of the numerical simulation show that, with the laminated thickness increasing, the thickness reduction ratio decreases, and the compaction implementing time and the resin distribution unsymmetry in the thickness direction increase. For the thicker laminate, compared with enhancing cure pressure, placing bleeder at both sides of the laminates improves the thickness reduction ratio significantly and gains a more uniform resin distribution.