With the emergence of the 6G technology, integrated sensing and communication (ISAC) has become a hot-spot vertical application. The low-altitude scenario is considered to be a significant use case of the ISAC. However, the existing channel model is hard to meet the demands of the sensing function. The radar-cross-section (RCS) is a critical feature for the sensing part, while accurate RCS data for the typical frequency band of ISAC are still lacking. Therefore, this paper conducts measurements and analysis of the RCS data of the unmanned aerial vehicles (UAVs) under multiple poses and angles in real flying conditions. The echo from a UAV is acquired in an anechoic chamber, and the RCS values are calculated. The results of different flying attitudes are analyzed, providing RCS features for the ISAC applications.