The establishment of a mathematical model of chaff cloud is to be calculated on the radar cross section. In this paper, “LayerAngleAngle” division method to be divided on the chaff cloud, to establish a number of parameters contain clouds of chaff chaff unit body, the use of power density and electric field strength and the reception point target these chaff unit body effective scattering area is calculated, and then the results of these chaff unit body superimposed, taking into account the interaction between them and shadow effects, the conclusion that the whole cloud of chaff RCS simulation model. Calculations show that the model can simulate RCS value chaff clouds many cases.