Automated fibre placement (AFP) enables the trajectory of unidirectional composite tape to be optimized,but laying down complex shapes with this technology can result in the introduction of defects.In order to solve this problem,the specimens are manufactured by an automated fiber machine which enables 2 prepreg fiber tows to be draped simultaneously,gap and overlap embedded defects are introduced on two cross-ply layups of [(90°/0°)5/90°] and [(0°/90°)5/0°].Autoclave cure without a caul plate results in local thickness variation and microstructural changes which depend on the defect type.This has a strong influence on mechanical performance. Use of a caul plate improves these variations.In the case of gap defects with fiber angle 0°,the tensile strength of the plate with a caul plate increased by 218.5%. In the case of overlap defects with fiber angle 0°,the tensile property of the plate with a caul plate is 69% higher than the plate without it. The direction of 90°fiber is not the main bearing layer,the caul plate is less effective in the defects with it.But the tensile property of the gap and overlap specimens with a caul plate is improved by 3.2% and 15.6% respectively.