Abstract: The multi-magnetic source resolution in spacecraft is a difficult problem in the field of magnetic survey. The technology based on the magnetic gradient tensor can be used for high resolution and high precision detection. In this paper, a spacecraft magnetic source model is established, and a multi-magnetic source model fitting method for spacecraft is proposed. The principal invariants of the magnetic field gradient tensor are used to determine the number and the horizontal location of the source, and the Euler equations are combined to complete the multi-magnetic source depth calculation, with best resolution up to 0.012 m, meeting the engineering requirements. The study opens up a new way of the multi-magnetic source target detection in spacecraft.