The enzymatic hydrolysates from the mandarin fish swim bladder， skin and bones was used for water retention on frozen mandarin fish. The degree of moisture loss slowed by the by-products hydrolysates on frozen mandarin fish was analyzed through soaking weight gain， defrosting loss rate and cooking loss rate. Using low field nuclear magnetic resonance spectrometer， texture analyzer， scanning electron microscopy（SEM）， the water binding status， texture characteristics and microstructure were measured respectively， to clarify the effect of by-products hydrolysates with salt on water binding capacity. The results showed that： the hydrolysates of swim bladder with 2.5% salt solution was effective in alleviating the defrosting loss rate of frozen mandarin fish and the decrease of cooking loss rate. The protective effect on frozen mandarin fish texture was remarkable. The integral area of movable water（T22） in mandarin fish is significantly larger than that in the blank group （P<0.05）， and also， the amount of intercept water in the muscle fiber was more than before treatment， which meant the overall fluidity weakened. The microstructure validates that the combined treatment of swim bladder hydrolysates with salt on frozen mandarin fish has a complete structure with strong muscle fibers and small gaps. Therefore， the quality of frozen mandarin fish can be maintained by the treatment of swim bladder hydrolysates with 2.5% salt solution， which can provide a theoretical basis for the development of a new type of phosphorus free water-retaining agent.