Abstract: This study presents an electrochemical detection method for detecting zinc content in seawater. This method firstly uses hydrothermal method to synthesize SiO₂@PDA-Sb composite material, and then the composite was modified on glassy carbon electrode to prepare SiO₂@PDA-Sb-Nafion/GCE for the determination of Zn²⁺ in seawater samples from the Pearl River Estuary using differential pulse anodic dissolution voltammetry (DPASV). The results show that Zn²⁺ has a strong dissolution peak on SiO₂@PDA-Sb-Nafion/GCE. Under optimal conditions, SiO₂@PDA-Sb-Nafion/GCE detected sensitively and accurately the Zn²⁺ in range of 1-1 000 nmol/L with detection limit of 0.71 nmol/L. The spike recovery experiment showed that the spike recovery rate of Zn²⁺ was 93.19%-100.12%, indicating that this method is applicable to the determination of Zn²⁺ in seawater samples on site. The method has the advantages of simple electrode fabrication, good stability and good anti-interference, and can improve the detection limit and accuracy of the existing determination method. It has a good application prospect for detecting trace Zn²⁺ in seawater.