Abstract: Distance measuring equipment (DME) is widely used in aviation industry for navigation. As the level of GNSS navigation signal on ground is low, it is actually easier to get interference from DME. BDS-3 has designed B2b signal in this frequency band, providing global navigation and positioning services, as well as global short messages, COSPAS-SARSAT return links service (RLS), and precision point positioning (PPP) services. It is extremely necessary to study the influence of DME signal on B2b signal. Based on the DME and B2b signal models, normalized power spectrum and anti-interference quality factor expressions were derived through numerical calculations. The interference tolerance and interference distance of B2b signals were analyzed, and the interference of DME signals on B2b signal was tested using a GNSS receiver. The calculation indicates that the DME station has an interference area of several kilometers to the B2b receiver, and the actual test shows that the B2b signal within 1 km of the DME station will be interfered. The research results can provide a useful reference for the subsequent anti-interference design of the BDS-3 B2b signal to obtain better services.