Abstract: In the Wangying-Liujia sag, Fuxin Basin, not only the CBM desorption volume is more than the adsorption gas, but the CBM origin is very complex. Research proves that the Wangying-Liujia CBM reservoir formation is greatly controlled by the diabase dike invasion, which is not only favorable for large hydrocarbon regeneration, but improves the Ro of the thick bituminite in the bottom of Fuxin formation, as the main gas origin. As the same time, the diabase dike invasion extremely improves the coal reservoir property, which is favour of the groundwater double replenishment following the coal seams outcrop ＆ diabase dike and the closed pressure water condition formation. Moreover, it is proved that there is abundant free gas in the Wangying-Liujia sag and the closed fault prevents gas diffusion. So the carbonite growing area is the most advantageous and the high production CBM wells will be distributed in the girdle band following the dike. In the same way, to the low rank CBM exploration, comparison the conventional nature gas research approach and combination the CBM＆conventional gas evaluation are important.