A power system for driving plural or multiple lamps includes a transformer circuit, a filter and steady-flow circuit, and a light source. The transformer circuit transforms a voltage level of an input AC signal, and includes a first output end for outputting a first AC signal, and a second output end for outputting a second AC signal. The first and second AC signals are opposite in phase. The filter and steady-flow circuit includes a first plurality of filter and steady-flow units connected to the first output end for suppressing harmonic signals of the first AC signal and outputting a plurality of third AC signals. The light source has a first plurality of lamps, each of which having one end connected to one of a respective one of the first plurality of filter and steady-flow units so as to be driven by a respective one of the third AC signals.