In this experiment, CoFeZn layered double hydroxide (LDH) was grown on the surface of foam nickel by hydrothermal method with metal nitrate as the metal source, urea as the precipitator, and ammonium fluoride as the structure directing agent. LDH (D-CoFeZn) with Zn²⁺ vacancy defect was obtained by alkaline etching. The effects of alkaline etching treatment and Zn content on the performance of electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were analyzed using a three-electrode system in 1 mol/L KOH aqueous solution. The results of morphology and structure show that both CoFe and CoFeZn LDHs are smooth nanorods, and alkaline etching results in the growth of smaller-sized nanosheets on the surface of CoFeZn LDH, but the valence states of the surface elements barely change. The electrochemical results show that Zn²⁺ vacancy defects greatly enhance the HER and OER performance of the electrocatalyst. The optimized D-CoFeZn-1 can achieve a current density of 100 mA·cm^-2 at only 224 mV for the HER and 236 mV for the OER, making it suitable for the all water electrolysis and superior to commercial catalysts in performance.