Objective: To optimize extraction and membrane separation technology of active polypeptides in Trionycis Carapax. Method: With extract yield and extraction amount of total polypeptides as evaluation indexes

orthogonal test was employed to optimize extraction process of polypeptides in Trionycis Carapax by taking solid-liquid ratio

extraction time and times as factors.Single factor tests were adopted to investigate membrane separation technology of active polypeptides in Trionycis Carapax with membrane permeation flux or efficacy as index. Result: Optimum extraction technology was as following:smashed vinegar Trionycis Carapax through a 24 mesh sieve

extracted three times with six-fold the amount of water for 3 hours each time;Extract yield was 11.71% and extraction amount of total polypeptides was up to 2.442 g.Membrane separation conditions were as follows:The concentration of polypeptides in Trionycis Carapax extract 6%

operating pressure of ultrafiltration membrane with relative molecule weight cut off of 20 and 8 KD running at 0.18-0.21 and 0.8 MPa

respectively;Under these operating conditions

retention rate of protein was 83.67%

purity of polypeptides(relative molecular mass<8 000) in Trionycis Carapax achieved 57.62%. Conclusion: Membrane separation techniques could be used for preparation of active polypeptides in Trionycis Carapax.