A power distribution system for applying electric power to a plurality of lighting units is provided. The power distribution system includes at least one user interface having a first pairing setting unit, a plurality of second pairing setting units, and a power line. The user interface is electrically connected with a power source. Each of the second pairing setting units is electrically connected with one of the lighting units, respectively. The power line connected with the lighting units is electrically connected between the first pairing setting unit and the second pairing setting units. Each of the second pairing setting units is capable of receiving an electrical signal output by the first pairing setting unit and determining whether the lighting unit controlled thereby is turned on or not. Therefore, each of the second pairing setting units connected with the same power line can be controlled individually.