Abstract: The eharaeteristies of variation ininhomogeneity of temporal-spatial distribution of stations with Radon anomaly observed befor strong earthquakes with magnitude of about 6 oecurred in North China are investigated.To deseribe the inhomogeneity of temporal-spatial distribution of observational station,showing Radon anomaly,Cv alue is employed.The results show that the Cv value distribution of short-term and imminent precursors increases and becomes more inhomogeneous before the strong earthquakes,which eould refleet the enhanecement of the erustal stresses.

Key words: Radon, Inhomogeneity, Strongearthquake, North China