Abstract:   Earthquake, Tsunami and nuclear explosion will affect the ionosphere. With the help of Global Navigation Satellite System (GNSS), the ionospheric effect of these phenomena can be well studied. Based on the IGS observed GNSS data, this paper obtains Travelling Ionospheric Disturbance (TID) from Slant Total Electron Content (STEC) and amplifies the disturbance by high order derivatives so as to identify the ionospheric disturbance induced by underground nuclear explosion (UNE). Finally, a new way for nuclear explosion identification is proposed which will be a convenient way to study UNE induced ionospheric effect.