Distortion analysis of SOI MOS transistor is presented.By the power series method,the distortion behaviors of FD (fully depleted) and RC (recessed channel) SOI MOS transistor configurations are investigated.It is shown that the distortion figures deteriorate with the scaling down of channel length,and the RC SOI device shows better distortion performance than the FD SOI device.At the same time,the experimental data show that the ineffective body contact can lead to an increase of the harmonic amplitude due to the bulk resistance.The presented results give an intuitive knowledge for the design of low distortion mixed signal integrated system.