Abstract: In order to determine reasonable coal preparation process for a certain central coal preparation plant whose raw coal is sourced from two different mines,washability of the raw coal was analyzed and the grouping-and-sizing way was used to judge whether the raw coal could accord with conditions of mixture washing and coal feed classified separation.Analysis shows that the raw coal of two mines adopted mixture washing could obey the rule of maximum yield,but it do not have grading condition.At last,the washability curve of this coal preparation plant was achieved comprehensively;it could provide theoretical support and technical guidance for selecting coal preparation and cleaning methods and technology process properly to achieve the best economic benefit.