Abstract: For H₂S-containing natural gas with pressures higher than 70 MPa, closer the distance between natural gas molecules is, stronger the association between H₂S molecules becomes. At such conditions, the traditional SRK, PR equations of state are difficult to accurately calculate the gas compressibility factors. In this paper, a total of 154 experimental compressibility factor data with pressure from 3.72 MPa to 97.58 MPa and H₂S contents from 0%-70.03% are used to improve the binary interaction parameters between H₂S and CH₄, CO₂ molecules for CPA(Cubic-Plus-Association)EoS and to evaluate the compressibility factor calculation accuracy of SRK, PR and CPA EoSs. Results show that the PR EoS has the highest accuracy and the average relative deviation is 1.12% for medium and low pressure natural gas (p < 35 MPa). The CPA equation has the highest accuracy with average relative of -1.46% for the high pressure and ultra-high pressure natural gas (p>35 MPa). Furthermore, the ST PVT cell is applied to measure a total of 138 compressibility factors for four H₂S-containing gas samples with pressures from 70 MPa to 131 MPa. The experimental results are used to verify the SRK, PR and CPA EoSs. Results demonstrate that CPA EoS has the highest accuracy for calculation of compressibility factors of ultra-high pressure and H₂S-containing gas.