The present application provides a double-beam laser polishing device and a double-beam laser polishing method for an aluminum alloy, which includes a frame; a rotary workbench and an optical path system, which are arranged on the frame. The optical path system includes: a first fiber laser, a second fiber laser, a first three-dimensional galvanometer, and a second three-dimensional galvanometer. The first three-dimensional galvanometer is connected with the first fiber laser through an optical fiber, and the second three-dimensional galvanometer is connected with the second fiber laser through an optical fiber. The first three-dimensional galvanometer and the second three-dimensional galvanometer are arranged side by side above the rotary workbench in a horizontal direction.