The aim is to explore the best extraction technology of gelatin from black carp skin in order to improve the additional output value of black carp. Black carp is one of the four indispensable fish in traditional freshwater culture in China. It is rich in high-quality trace elements such as protein, phosphorus, selenium, iodine, iron and calcium, which are beneficial to human health. However, at present, in the processing of black carp, except fish products, black carp skin as a by-product has not been fully developed and utilized, and its potential economic value has not been fully tapped, resulting in a great waste of resources. Black carp skin is rich in collagen and is an ideal raw material for extracting gelatin. In this work, the effects of ultrasonic time, enzyme dosage, enzymolysis time and enzymolysis temperature on the extraction yield of gelatin from black carp skin were systematically studied by single factor experiment and Box-Behnken experimental design. Gelatin was extracted from black carp skin by ultrasonic treatment and enzymatic hydrolysis. The influence range and trend of each process were preliminarily determined by single factor experiment. Based on the results of single factor experiment, ultrasonic time, enzyme dosage, enzymolysis time and enzymolysis temperature were selected as key process parameters, and Box-Behnken experimental design was carried out. Through regression analysis, a regression model was established to predict the extraction yield of gelatin, and the optimum extraction conditions were determined. The results showed that the optimum extraction conditions of black carp skin gelatin were ultrasonic time 125 min, enzyme dosage 0.22%, enzymolysis time 154 min and enzymolysis temperature 45℃. Under this condition, three parallel experiments were carried out, and the average extraction yield of gelatin from black carp skin was 18.28%, and the relative error between it and the predicted value was only 0.22%, which indicated that the constructed regression model had high reliability and accuracy. In addition, the extracted gelatin was characterized by FTIR. The results showed that the extracted substances had the basic characteristics of gelatin, such as amide A band, amide I band, amide II band and amide III band, which further confirmed the gelatin properties of the extracted substances. This study provided a technical reference for the development and application of black carp skin resources in gelatin and related products. By optimizing the extraction process, the high-value utilization of black carp skin can be realized, which contributed to the sustainable development of aquatic processing industry. At the same time, it also provides reference and enlightenment for the development and utilization of other fish skin resources.