The gray correlativity analysis was applied to study the effect of dominantfactors on net-production-cost in high-yield-fish-pond for the Pearl River Delta and YangtzeDelta. The dominant factors effected on net-yield were input of grasses, input of figerings,and the dominant factor effected on net-production-cost was input of grasses in Pearl RiverDelta. As for the Yangtze Delta, the dominant factors effect on net-yield were input of spiralshell, input of fingerings, and the dominant factors effected on net-production-cost wereinput of fingerings and input of spiral shell. The gray dynamics models GM(1, 2) of net-yieldfor these areas were built by using dominant factors.