Abstract: The geosound records of Lulong and Changli stations before Luanxian earth-quake of magnitude 5.0 are published in this paper, and a element analysis for the possible propagation distance of geosound signals by means of geosound source intensity is given. It indicat that the geosounds don't come from focus, but come from neighbouring regin around observation stations under ground. Therefore, the receiving signal sequences between several stations are incor-relation when they are far apart each other. Nevertheless, for the focus volume is in proportion to the magnitude, we will still probable detect the precusory informations in vast arear and at earlier time prior to earthquakes for greater shakes.