Abstract: The non-woven ultrathin fibers film with a thickness about 0.1mm was made by use of electrospinning. This film was incorporated into the middle interface of a composite laminate, which was cured and cut into double cantilever beam (DCB) specimens. Blank DCB specimens were prepared in the same way. The mode Ⅰ interlaminar fracture toughness was measured according to ASTM D5528 standard. The experimental results show that the mode Ⅰ critical strain energy release rate is improved about 35% by using the non-woven film compared to the blank specimens. The propagation of cracks for those two kinds of specimens is analyzed by use of the FE method. It shows that the numerical results are well in agreement with the experimental results and a better understanding of the fracture mechanics is obtained by the numerical analysis.