In this study, chickens gizzard-membrane processed products were used as the raw materials. The effects of chickens gizzard-membrane processed products prepared by different methods on the in vitro digestion characteristics of soybean protein isolate were compared through analyzing the digestibility, enzyme activity, particle size and relative molecular mass weight distribution. The results showed that the protease in chickens gizzard-membrane processed products might be the main cause of protein degradation in the absence of exogenous enzymes. In the presence of an exogenous protease, digestibility of soybean protein isolate increased upon the addition of chickens gizzard-membrane, and the effects of the processed products on protein digestibility followed this order: wheat bran stir-frying > vinegar stir-frying > raw product > sand stir-frying > plain stir-frying. The effect of a chickens gizzard-membrane processed product on protein digestibility was consistent with its promotion effect on enzyme activity. The wheat bran stir-frying and vinegar stir-frying chickens gizzard-membrane promoted protein digestibility the most after 1 h digestion, enabling the increase of the digestibility of soybean protein isolate from 36.78% to 41.33% and 40.99%, respectively. The results of in vitro digestion characterization also showed that the addition of chickens gizzard-membrane decreased the particle size of protein digestion products, and shifted the maximum peak of particle size distribution to the left, and the relative molecular mass weight distribution of protein towards the smaller molecular range. The influence of chickens gizzard-membrane on digestive products occurred mainly within the first one hour of digestion. This study provides a new idea for the in-depth study of chickens gizzard-membrane.