Abstract: Elastic impedance inversion has been proved to be more sensitive in lithology detection than conventional wave impedance inversion mainly based on the hypothesis of seismic wave vertical incidence while AVO effect is considered when it comes to elastic inversion. This inversion method almost gets rid of the hypothesis of AI, and reserves the characteristics of seismic reflection amplitude versus offset or incident angle. The concept of coal body structure ratio P is brought up by the combination of both elastic inversion and conventional wave impedance. It is learned by both numerical analysis and actual inverted results that tectonic coal develops with high potential when P value is greater than or equal to 2.5. Studies indicate that it is effective and practical to predict tectonic coal zone with the ratio P.