Abstract: By measuring bulk density and true relative density of raw coal under different conditions of moisture and particle sizes through a period，this paper collects and analyses testing data by using mathematical and statistical methods such as the Grubbs test and binary linear regression. It verified the binary linear relationship between coal moisture/coal particle size and bulk density based on the experimental data of true relative density of coal.

Key words: Grubbs test, Binary linear regression, Bulk density, Total moisture, Particle size