As an important model for modeling synthetic aperture radar (SAR) image data

G0 distribution has strong modeling ability and good practicability

and therefore draws extensive attentions around the world.The applications of G0 distribution require accurate and effective parameter estimations

and maximum likelihood estimator

which is statistically optimal

has not been applied for the G0 distribution due to the complexity of G0 distribution.In this paper

a new derivation of G0 distribution is first given

based on which

a maximum likelihood parameter estimation method using expectation maximization (EM) algorithm is proposed for the G0 ditribution.The proposed method is compared with other G0 parameter estimation methods through extensive experiments

and the results show the effectiveness of the proposed method.