Abstract: In radar systems, it is feasible that amplitude probability density function (APDF) is analytically known and tractable for CFAR processing and detection. Unfortunately, there is no closed-form expression for the probability density function of envelop of stable clutter. To overcome such challenge, we develop a closed-form model to approximate actual APDF of isotropic stable clutter for α（1,2. Proposed model fits actual APDF well while keeps concise, and hence, tractable form. Simulation results illustrate that proposed model is a valid approximation to actual APDF of stable clutter. Via Logarithm moment, a new approach to estimate parameters of clutter from series of isotropic stable clutter envelop is further proposed.