Abstract: This paper tested part performance of the latest developed portable calibration apparatus of mass spectrometers for partial pressure. The ultimate vacuum of the device was measured using a reference ionization gauge; The diameter and the thickness of the gas-operated element which conductance is about 10⁻² m³/s could be measured accurately and the conductance was calculated using formular under the molecular flow condition. The conductance of the gas-intaked conductance elements with micro-meter apertures was measured using constant volume experiments. The back-streaming ratio is obtained using the same vacuum gauge to measure the gas pressure at both sides of the gas-operated conductance elements. The experimental results proved that the ultimate vacuum of the device is 4.8×10⁻⁷ Pa. The conductance of the gas-exhausted element for N₂ is 1.37×10⁻² m³/s. The conductance of two gas-intaked conductance elements for N₂ are 3.81×10⁻⁶ m³/s and 4.50×10⁻⁸ m³/s respectively. The back-streaming ratio for N₂ is 0.193 .Based on analysis, the calibration range of the device for N₂ is （4×10⁻²～5×10⁻⁶）Pa.