Provided are a method of preparing a nanowire grid polarizer, and a nanowire grid polarizer prepared using the same. The method includes: mixing a surfactant and a silica precursor to prepare a mesoporous film composition; coating the mesoporous film composition on a substrate; aging the coated product to form a silica template composite; removing the surfactant inside the silica template composite to prepare a mesoporous material having channels; and filling the channels of the mesoporous material with metal. The method is suitable for the formation of a nanowire having a stable structure, mass production, and large-area production.