Features of geopetal structures in Carboniferous Kalagang volcanic rock that develops at Niudong Block in Santanghu Basin are similar to common structures of carbonate rock. The geopetal structures in the Kalagang volcanic rock commonly develop in vesicles and autoclased fractures. In geopetal structures, the filling of vesicles and autoclased fractures has two parts that the percolating mud is usually under the interface and the crystal natrolite and other authigenic minerals are mostly on the top. The interface between both is parallel. In addition, the dissolution of amygdaloidal is often companied with the geopetal structures. Analysis has shown that the features of geopetal structures and the dissolutions of amygdaloidal nearby geopetal structures are relative in origin with the eluviation of leached zone. The dissolutions of amygdaloidal companying with geopetal structures and the remainder vesicles in which authigenic minerals are not full greatly improve reservoir capability of the volcanic rock. Discover of geopetal structures in the volcanic rock has a great geological significance in identifying the top and the bottom of volcanic formation and the classification of volcanic facies as well as petroleum exploration.