The invention discloses an integrated transformer station low-voltage unit of offshore new energy and a mounting method thereof. The low-voltage unit comprises a housing, elements and mounting plates. The elements consist of an inlet wire device, an outlet wire device, an inlet wire operation indication device, and an outlet wire operation indication device. The mounting plates include a main inlet mounting plate, an outlet wire mounting plate, and an operation panel. All elements are installed at corresponding mounting plates in an integrated mode by using loops as modules, thereby forming corresponding loop modules. According to the invention, arrangement is realized by using loops as modules and the assembly line type working mode is employed; and all loop module elements are assembled separately outside the low-voltage unit, thereby realizing synchronous, rapid and high-efficiency assembling of all loop modules and the low-voltage unit. With the corresponding mounting plates, non-exposed charged bodies are formed in front of the cabinet, thereby effectively preventing an electric shock accident. And installation sequences of the operation unit formed by operation indication devices and the loop modules are consistent and division is carried out based on loops, so that user can carry out operation, maintenance, and repairing conveniently.