The dynamic RCS of an aircraft target varies dramatically with target geometry and motion information (position and velocity), the values fluctuate and have no pattern. So the fluctuation models are often adopted to describe the statistical nature of dynamic RCS. In this paper, we first introduce a simulation method of dynamic RCS for aircraft target. Secondly, a brief introduction of Chi2 distribution and Lognormal distribution model is given, and Gaus- sian Mixture distribution is proposed in order to describe the fluctuation more accurately. The parameter estimation method is discussed in detail to find the best fitting result. As an exam- ple, the dynamic RCS data of an aircraft target are analyzed with Chi2 distribution, Lognormal distribution model and Gaussian Mixture distribution. The fitting results show Gaussian Mix- ture distribution can provide a better approximation of the dynamic RCS than the other two distributions in accordance with error-of-fit and Kolmogorov-Smirnov fitting goodness test.