Abstract: In order to evaluate the distribution of measured vitrinite reflectance data,Gini coefficient was applied in this study.Three groups of coal samples were prepared for the measurement of vitrinite reflectance,namely the original sample(Y₁),water washed sample (Y₂) and exinite enriched sample(Y₃) after denstty centrifuge separation.Gini coefficients were calculated and compared among them afterwards. The smaller Gini coefficient of Y₂ indicates a better kurtosis in the distribution of vitrinite reflectance,which can be explained by the effect of washing.On the other hand,the larger Gini coefficient of Y₃,a worse kurtosis in reflectance distribution,can be explained by both water-washing (right shift) and exinite enrichment (left shift).The Gini coefficient is expected to be applied further to sedimentary source and provenance studies in the future.