Abstract: In response to the requirements for measuring and calibrating the ambient neutral gas's pressure during the spacecraft's in-orbit operation, this research focuses on the ground simulation of high-speed spatially directional molecular flow and the associated pressure calibration methods. Based on the approach of ion beam surface neutralization, a single type of gas is employed to simulate the pressure effect of spatially directional molecular flow. By establishing a model for the transmission process of the beam and conducting quantitative analyses of the ion beam's acceleration, extraction, neutralization, and transmission processes, a calibration method for pressure sensors in spatially directional molecular flow has been developed. This method offers a reference for the ground simulation and pressure calibration of high-speed directional molecular flows. It can be used to guide the development of pressure sensors for spatially directional flow and their corresponding ground calibration devices.