Study on the SMPS Effectiontely Save Energy Electronic Ballast Wang Mingyang (Assoc. Prof.,Institute of Mechanical & Electrical Engineering, WUT,Wuhan 430070,China.) This paper described the construction and theory of the effectiontely save energy with SMPS. The solve method on common conduct,Cross lass and saturation lass with harm action has been offered. After the GJD electronic ballast transferred possession to the factory,society and economy benefie has been gained good. ballast; SMPS; harmonic analyse; series connection resonance; common conduct