In order to realize dimension reduction detection of satellite-borne GPS receivers, the working mode and on-orbit historical fault mode of GPS receivers are analyzed, and a dimension reduction detection method of satellite-borne GPS receivers based on principal component analysis is proposed. The main components of the fault alarm variables are extracted from the on-orbit fault data samples of a satellite GPS receiver, and the fault features are effectively reduced in dimension, which is verified by historical fault simulation. The dimension reduction detection of satellite-borne GPS receivers is of great significance for ensuring the safe and stable operation of satellites in orbit and effectively realizing their mission.