The efficiency of capacitor charging power supply (CCPS) is an important index. Improving the efficiency is not only the demand for efficient using of power energy, but also the necessity for ensuring the charging rate, device safety and electromagnetic compatibility. The power loss of inverter, LC resonance, voltage rising and harmonic distortion are the main influence factors. So the measures of soft-switching, improving power factor, reducing total harmonic distortion (THD) of harmonics should be taken to decrease the total power loss.