Abstract: In order to compare the accuracy of adsorption property determination of the HCA high pressure volume adsorption test device and i Sorb HP2 high pressur e gas adsorparison analyzer,the author took the coking coal of Shaqu mine as the study object,the measurement results of the two devices were compared. The results sho wed that there were big differences existed in the adsorption constants obtained from the two instruments,the adsorption constant a obtained from HCA high pressure volu me adsorption device would be smaller than the i Sorb HP2 high pressure adsorption analyzer,the differences were within5. 557 6~ 5. 994 0 cm3/ g. b value on the contra ry,the differences were within 0.501 4 ~ 0. 664 4 MPa- 1. According to the test measured a and b value,the original gas content of the seam and the site measured original gas content were compared,the error of HCA high pressure volume adsorption device was within- 0. 91 ~ 2. 47 m3/ t,the error of i Sorb HP2 high pressure gas adsorption analyzer was within- 0. 09 ~- 2.92 m3/ t. Although the difference of the adsorption constants measured from the two instruments was big, but the error would be small when calculating the original gas content of the coal.