Abstract: In order to investigate the influence of coal moisture and fineness on bulk density,the variance analysis of moisture( M),medium diameter( d50) and distribution parameter( n),which were the important factors influencing coal bulk density were conducted by orthogonal test. The results showed that the influence of moisture and interaction of medium diameter and distribution parameter was significant. The lower moisture and wider size distribution helped to improve the coal bulk density. The medium diameter was proportional to the bulk density. Basically,when the M,n,d50 was 5%,0. 5,1. 5 mm respectively,the coal bulk density was the best and the size composition was 75. 69%.