Two kinds of high-nuclear molybdenum clusters (NH4)12[Mo36O108(NO)4(H2O)16]?33H2O and [Mo36O112(OH2)16 (H2bipy)4]?28H2O were synthesized. Inhibition mechanisms on diphenolase activity of tyrosianase, anti-melanosis effects of Litopenaeus vannamei and preservation of Mo36 and Mo36-bipy were investigated. The result showed that the IC50 values of tyrosine diphenolase respectively were 0.0358 mmol/L and 0.0601 mmol/L. The inhibitory effect of Mo36 on tyrosinase was reversible competitive inhibition, the inhibition of tyrosinase by Mo36-bipy was reversible mixed inhibition, and the inhibitory effect of Mo36 on tyrosinase activity was better than that of Mo36-bipy. Litopenaeus vannamei was stored under 4 ℃ environment for 10 days, and the sensory score, color, pH value, TVB-N and total number of colonies was detected. It was found that the high-nuclear molybdenum clusters had a certain preservation effect on Litopenaeus vannamei (p<0.05). Mo36 and Mo36-bipy can significantly improve the value of sensory score and L*, and reduce the pH value and the total number of colonies. This paper can provide experimental basis for the preservation of the Litopenaeus vannamei body and the application of polyoxometalates to new areas.