The invention relates to a judgement method and device for avoiding spectrum sensing blind areas interfering a GEO system. The method includes the following steps: (1) determining the area in which an NGEO system can detect the GEO system according to input parameters; 2) determining the area that the NGEO system causes interference on the GEO system; (3) determining blind areas of spectrum sensing according to the size of power of signals of the GEO system received by the NGEO system and epfd value of interference on the GEO system from the NGEO system. In the scene that GEO and NGEO satellite systems share spectrum, the GEO system as the main user judge whether there are blind areas of spectrum sensing in the NGEO system detection process or not, and harmful interference to the GEO system is avoided effectively. The method and device can be widely applied in the field of satellite communications.