Abstract: Magmatic invasion into No.8 coal seam is a relatively severe problem in the north mining district no.2 of Wolonghu mine, bringing out significant methane enrichment. Acoustic impedance obtained by restrained inversion using both seismic data and well log, along with other seismic attributes picked out by step-wise regression, is considered as an external attribute to predict porosity using the technology of probabilistic neural network(PNN). PNN has higher definition in identifying gas enrichment zone than acoustic impedance,while they both indicate the same lithological interpretation.In conclusion, PNN is a highly reliable and effective method of lithological inversion to study tectonic coal development and methane gas occurrence with a high stability and computational precision.