Abstract: Differential mode technology which alleviates th e conflict between Sum and Difference patterns and improves antenna efficiency i s playing a more and more important role in LEO remote sensing satellite receivi ng systems. A monopulse tracking technology of differential mode with emphasis o n its working principle and realization method, and points for attention is intr oduced in this paper. The technology has a significant effect on the practial pr oject by its adaptability to many signal forms and its higher reliability.