To improve the nutritional and processing characteristics of traditional mud carp surimi-based products, the effects of egg white supplementation (0~50 wt.%) on the nutritional quality and functional properties of mixed protein slurry systems composed of mud carp surimi and egg white were systematically investigated. Protein nutritional quality was evaluated using the FAO/WHO reference pattern and the whole-egg model, incorporating chemical score, amino acid score, essential amino acid index, and biological value. Processing characteristics were analyzed using rotational rheometry, texture analysis, and Fourier-transform infrared spectroscopy to assess rheological behavior, gel properties, and foaming performance. The results showed that egg white supplementation significantly improved amino acid composition. Under the FAO/WHO reference pattern, the ratio coefficient of sulfur-containing amino acids increased from 0.84 to 1.25 (P<0.05), while under the whole-egg model it increased from 0.69 to 1.04 (P<0.05). The biological value increased from 90.19 to 95.45 (P<0.05). In terms of functional properties, supplementation with 40 wt.% egg white elevated foaming capacity from 13.80% to 47.00% (P<0.05), while foam stability remained at 93.62% after 60 min (P<0.05). The highest gel strength, 31.15 g•cm (P<0.05), was also achieved at an egg white supplementation level of 40 wt.%. Overall, supplementation with 40 wt.% egg white markedly enhanced both the nutritional value and processing characteristics of mud carp surimi slurry through amino acid complementation and synergistic protein interactions. These results identify this formulation as an optimal composition for achieving balanced nutritional quality and functional performance, and provide theoretical support for the industrial optimization of traditional composite protein products, such as wrinkled fish curd, and the development of novel high-nutrition surimi-based products.