In this paper, a CMOS class-E power amplifier with power control is presented. Its output power could be varied over a broad range with high efficiency by utilizing the combination of the parallel amplification technique and the drain modulation technique. The drain modulation is implemented as a class-S modulator and the output powers of the parallel amplifiers are combined with quarter-wavelength transmission lines. The simulation results show that the power amplifier could achieves a maximum power-added efficiency (PAE) of 47.9% and maintain a PAE higher than 41% over the 140-700mW output power range.