Abstract: Small target detection in sea clutter is a very important problem in radar signal processing.In this paper,from the analysis of sea clutter doppler spectrum characteristics,we present a sea clutter statistical model based on joint rayleigh distribution,and a waveform entropy feature to describe the energy extend degree of sea clutter Doppler spectrum.On basis of these,the small target detectors in sea clutter are presented.The detectors have been verified with the data collected by McMaster IPIX radar at the east coast of canada.