In view of the current unsatisfactory processing performance of existing banana stalk fiber extraction machine， by drawing on the design principle of manual razor, design a two-layer asymptotic blade structure to optimize its performance. A comparison test was made between the improved blade and the ordinary L-shaped blade. The results showed that the fiber extraction rate increased from 14.50% to 16.03%, and the fiber content decreased from 14.21% to 9.85%. The processing efficiency was more stable when multiple pieces of stalks were stacked.