Abstract: Study in campus network quickly determined the position of abnormal invasion method.This paper puts forward area associated probability detection method invasion.Network node in the relationship between as the foundation, according to the area and its surrounding area was invaded our interdependence on each other, the connection degree is estimated to be abnormal invasion of the region associated probability.Use probability decision thought iteration lock was invaded area.The experiment shows that, by using the method can improve the campus network for the efficiency of the abnormal invasion position, so as to ensure the security of campus network.