To address the poor nutrition and limited functionality of traditional fish cakes, a dual-protein quinoa fish cake was developed using grass carp surimi, quinoa flour, soy protein isolate (SPI), whey protein (WP), and TG enzyme. Single-factor and response surface experiments were conducted to optimize SPI, WP, TG enzyme, and quinoa flour levels based on sensory and water retention scores. Results showed that SPI had the greatest impact on quality, followed by WP, TG enzyme, and quinoa flour. The optimal formula was: SPI 4.3%, WP 0.3%, TG enzyme 0.4%, quinoa flour 8.1%, yielding a composite score of 93.1 (close to the predicted value). The optimized fish cake exhibited good elasticity, water retention, sensory quality, quinoa flavor, and high nutritional value. These findings provide a reference for using quinoa in surimi products and developing healthy fish cakes.