Abstract: Based on the research on the statistical property of decision variables,this paper analyzes theoretically the influences of threshold and dwell time on the false-alarm probability and the detection probability under constant false-alarm rate(CFAR) criteria.A method to design the threshold and dwell time is proposed in which the threshold is expressed in the relationship of the false-alarm probability,the cells searched in one pass and the non-coherent integrations,and the dwell time is related to the false-alarm probability,the detection probability,the cells searched in one pass and the carrier-to-noise ratio.Simulation results demonstrate that the proposed method is correct.