The work aims to extract chondroitin sulfate in the alkali-salt method with the egg shell membrane as raw material. The polysaccharide extraction rate was used as index to study the effects of extraction time, extraction temperature, alkali-salt ratio and liquid-solid ratio on the test. On the basis of single factor test, various conditions of test were analyzed and optimized in the response surface method. The experiment results showed that, the best process parameters for the extraction of egg shell membrane were as follows: extraction time of 8 h, extraction temperature of 65 ℃, alkali-salt ratio of 6∶1, and liquid-to-solid ratio of 15∶1. Under these conditions, the extraction rate of chondroitin sulfate was 74.0%. The response surface design test and verification test show that the proposed optimal reaction condition is reliable and feasible.