Abstract: The pumping speed of high vacuum/ultra-high vacuum (HV/UHV) pumps is commonly tested by combining the flow-rate method with the conductance method under the pressure range of 10⁻¹ to 10⁻⁶ Pa. Nevertheless, this technique is constrained by drawbacks including the narrow inlet-pressure range of the test dome and large measurement uncertainty of test results. This paper proposes a novel pumping-speed measurement approach for HV/UHV pumps, which employs a symmetrically structured test dome coupled with a standard conductance element. In this symmetric configuration, two identical test domes are fitted, respectively, with the pump-under-test and the standard conductance element. Vacuum gauges are utilized as comparators to measure gas pressures induced by the identical gas flow rate in the two test domes. The pumping speed of the pump under test for a given gas is calculated by taking the molecular conductance of the standard conductance element for that specific gas as the reference standard. The proposed method overcomes the limitations of conventional techniques, such as the considerable deviations in the absolute-pressure readings of vacuum gauges and the restriction to equivalent-gas pumping-speed measurement. Furthermore, it eliminates the requirement for a known standard gas flow rate and enables pumping-speed measurement over the pressure interval of 10⁻¹ to 10⁻⁷ Pa in the test dome. The combined standard uncertainty of the measured results is reduced to 2.5%.