In order to investigate the effect of precursor powders on the electrochemical performance of Ag/AgCl electrodes, AgCl powder was prepared by adding surfactant and different drying methods using solid-phase ball milling method. An optimized preparation process was found, and Ag/AgCl porous electrode was prepared. The microstructure of the powder was analyzed and characterized by SEM and XRD; the electrochemical performance of the electrode was tested by the eDAQ electrochemical workstation and low-noise preamp noise test device to test, and the effect of microstructure on the polarization performance, short-term stability and electrochemical noise level of the electrode were discussed，and its external electric field response performance was tested. The results show that AgCl powder prepared by freeze-drying method with CTAC (cetyltrimethylammonium chloride) ball mill added to solid phase mill for 4 h has good dispersibility, uniform morphology and particle size below 1 μm; The prepared composite Ag/AgCl electrode has a porous structure with an open porosity of about 32.78%; the electrode has a large exchange current density of about 1.003 5 A·cm-2, which is not easily polarized; the two electrodes have good consistency and a small potential difference about 0.005 mV; the electrode has excellent short-term stability, the electrode potential fluctuation does not exceed 0.01 mV/24 h, and the power spectral density can be as low as 1.02 nV/Hz at 1 Hz frequency, which provides an extremely favorable test basis for underwater weak electric field detection.