Abstract: For each transmitter-receiver channel of distributed multiple-input multiple-output(MIMO) sky-wave over the horizon radar, the elevation and azimuth angle of input and back scatter direction relative to the observed sea surface is calculated by means of numerical ray tracing, the formula of the first and second order sea clutter normalized raldar cross section(RCS) is derived. After convoluting with Doppler transfer function of the transmitting and receiving channel, the sea clutter power spectrum of receiver is obtained by combining with the radar equation. The random time sequences of sea clutter plus noise is simulated based on the power spectrum, of which characteristics is analyzed concisely.