The physical and mechanical properties of coal and rock can provide basis for engineering geologicalevaluation,engineering building design and rock mechanics related scientific research.The apparent density ofcoal and rock can reflect the merits and demerits of mechanical properties of coal and rock.By placing coalblocks in a measuring cylinder filled with liquid paraffin ,the volume of coal blocks is determined according tothe change of liquid level in the measuring cylinder, and then the apparent density of coal and rock mass isobtained according to the basic density formula( mass divided by volume).Compared with wax sealing method.this method is simple and fast.Through T-test on the apparent density measurement results of two kinds of coaand rock blocks.it is concluded that there is no significant difference between the apparent density measuredby two methods.The simple determination method of apparent density of coal rock can replace the wax sealmethod and be used for the rapid determination of apparent density of coal rock.