Abstract: To obtain high quality co-precipitated dual proteins with desirable functional properties and enhanced nutritional value, this study systematically evaluated the effects of varying dissolution pH levels (2.0, 3.0, 9.0, 10.0, and 11.0) on the nutritional and physicochemical properties of pea-grass carp dual protein (Co). Parameters including optimal precipitation pH, proximate composition, particle size, zeta potential, protein subunit composition, amino acid profile, and digestibility were analyzed. Results indicated that the optimal precipitation pH for Co was 5.0. All Co samples prepared by the pH cycling method were identified as high-quality proteins, containing major heterologous protein subunits and a full spectrum of amino acids, with methionine content significantly higher than that of pea protein alone. Physicochemical analyses revealed that alkaline-processed Co samples (Co9, Co10, and Co11) exhibited higher α-helix and lower β-sheet ratios compared to acid-processed ones (Co2, Co3). SDS-PAGE results demonstrated that the alkaline method facilitated the enrichment of readily digestible protein fractions. Alkaline-processed Co also showed smaller particle sizes and higher absolute zeta potential values. Nutritional profiling indicated that Co10 had a crude protein content of 86.98%, an essential-to-total amino acid ratio of 40%, and in vitro protein digestibility and corrected amino acid score of 86.16% and 1.04, respectively. These attributes support the commercial potential of Co10. In conclusion, the alkaline pH cycling method represents a promising approach for preparing pea–grass carp dual protein with superior nutritional benefits..