In this paper， four Dawson-type polyoxometalates of P2Mo17Ni， P2Mo17Cr， P2Mo17Co and P2Mo18 were synthesized and characterized. The electrochemical properties of four polyoxometalates aqueous solutions at different polyoxometalates concentrations and different sweep rates were studied by cyclic voltammetry. And under suitable conditions to catalyze different concentrations of tyrosinase， the catalysis of polyoxometalates aqueous solutions on tyrosinase was studied. The results showed that the redox processes of the four compounds belong to the diffusion control process. The electrochemical sensing of tyrosinase all showed good stability， and there was a good linear relationship between the response current and tyrosinase content， and the detection effect of P2Mo17Ni was the best among the four compounds. The chronoamperometric curve shows that the lowest detection limit (S/N=3) of P2Mo17Ni for tyrosinase can reach 0.4095 U/mL. When this method is applied to the detection of tyrosinase content in shrimp， the sample recovery rate is 98.0477%-99.5872%， and the method has good selectivity. When multiple interfering substances coexist， the detection result is almost unaffected. It shows that the modified electrode has high accuracy and stability. This study provides a theoretical basis for the application of this method to detect the content of tyrosinase in Penaeus vannamei and other aquatic products， and to realize the quality evaluation of Penaeus vannamei and other aquatic products.