The invention discloses a silver nanowire/hydrotalcite composite electrocatalyst and a preparation method thereof. The preparation method includes: step A, dispersing silver nanowire solution and surface growth regulator into mixed transition metal salt solution; step B, dropwise adding mixed alkali solution into the above solution, controlling pH of the solution to 8.8-10.0, crystallizing at roomtemperature, and drying to obtain the s silver nanowire/hydrotalcite composite electrocatalyst. Ag-based catalyst used in the preparation method is relatively low in cost in heavy metal and has quitehigh alkali resistance in alkaline conditions, thereby being suitable for serving as an oxygen evolution catalyst to be applied in chlorine alkali industry in highly-alkaline conditions. By controlling vertical growth of hydrotalcite on the surfaces of silver nanowires with large surface area, quantity of hydrotalcite on the surfaces of silver wires by unit mass is increased; electroconductivityof Ag and a diffusion passage provided by hydrotalcite are utilized, so that catalytic efficiency is improved; the synthesis process is simple and control.