The honeycomb sandwich structure composite material is formed by automated fiber placement technology,lateral pressure deformation of honeycomb core and prepreg fiber bridging are defects, the formation mechanism and influencing factors of them are analyzed. Design concave molding tooling for two kinds of molding process, adhesive film pre-bonding process and taws zero-tension technique have been proposed to avoid defects. Completing the laying of the flatbed honeycomb sandwich, comparing the parts after curing: its cannot avoid the prepreg fiber bridging use concave module, and bridging position appears stratified, lack of resin defect; convex module is more suitable. The results can provide the reference for forming complex honeycomb sandwich structure composite material.