A mineral association has been named the daughter group and its original materials(meterial source) have been named mother group,the later can consist of a single material,i.e.a single material source,or of several meterial sources in a certain propotion,i.e.compound material source.Generally,the minerals contained in daughter group must appear in mother group, but minerals that were not contained in daughter group must not appear. Quantitatively,the proportation of various minerals in daughter group should be approximately similar to one in mother group. According to the rule stated above,by means of fuzzy mathematics the author gives out a mathematical model based on actual mineral species and quatity,in order to calculate possibility that this mineral association originates from another mineral association.Taking the West Talimu Basin as an example,the paper discusses the .practicl of this effect of model.