Double energy accelerator used in custom security monitoring is powered by the high-power magnetron, the top of pulse current waveform through the magnetron varies greatly in the double energy operation mode of the ordinary solid-state modulator due to nonlinear impedance of the magnetron, thus it is difficult to precisely distinguish contraband from the commodity in the cargo. To make the top of the pulse current waveform through the magnetron used in the double energy accelerator flat in the double energy operation mode, we developed a solid state modulator based on dual-loop parallel circuit topology, parallel IGBT solid state switch, high ratio pulse transformer technology and waveform correction technique for double energy accelerator. When the operating current through the magnetron is in the range of 70～120 A , this solid state modulator can output quasi-trapezoid current waveform in the double energy operation mode, and the relative top fluctuation of the pulse waveforms through the magnetron is less than 5%.