A multi-source low-power low-temperature plasma polymerized coating device and method belong to the technical field of plasma. In the device, a plurality of discharge cavities are mounted on the wall of a main vacuum chamber; a plane grounding grid mesh and a porous electrode plate are mounted in each discharge cavity; and the porous electrode plate is parallel to the grid mesh, keeps a gap with the grid mesh and is connected with a low-power high-frequency power source. A carrier gas pipeline and a monomer steam pipeline are respectively connected to each discharge cavity. To-be-treated base material is placed in the main vacuum chamber. The vacuum pump is started to feed carrier gas and monomer steam. The wall of the discharge cavity is discharged by the porous electrode plate; the monomer steam is polymerized; and the polymerisate passes through small holes and the grid mesh successively in the porous electrode plate to enter the vacuum chamber and deposit on the surface of the base material to form a polymer coating. The device of the present invention has the advantages of even spatial distribution of plasma, good quality uniformity of products under batch treatment, low plasma energy and density, difficult in excessively destroying a chemical monomer structure and good quality of the formed polymer coating.