Abstract: The bistatic synthetic aperture radar system with the global satellite navigation system (GNSS-SAR) as the transmitter possesses advantages such as all-weather operation and strong sustainable monitoring capabilities. Regarding the BeiDou Navigation Satellite System (BDS), previous studies mainly concentrated on the traditional B1I and B3I signals. With the full operation of the BeiDou-3 Navigation Satellite System (BDS-3), the newly added signals such as B1C, B2a, and B2b have a larger bandwidth, presenting new opportunities for the GNSS-SAR system. This paper analyzes the imaging resolution performance of BDS-3 signals under different geometric configurations, employs the generalized ambiguity function (GAF) to analyze the imaging performance of BDS-3 signals, and verifies it through simulation. The research results indicate that the geometric configuration has a considerable influence on the resolution performance of the GNSS-SAR system. The minimum resolution distance of different navigation signals of BDS-3 is approximately 18 m, the maximum resolution distance of B2a and B3I is about 30 m, and the maximum resolution performance difference between B1C and B1I is significant, being 20 m and 50 m respectively.