The paleo-harst of Qianmiqiao carbonate buried hill can be divided into two types, the weathering shell harst and the fracture-cavity harst. The paper discussed detailedly the distinguish characteristic of petrology, mineralogy and isotope geochemistry of above types. Combined the results of exploration and development, some points were put forward: a.The distribution of gas trap was controlled by the top of structure; b. The effectual reservoir distributed within about 200 meter to the weathering shell top and was controlled by the weathering shell harst; c. The fracture-cavity harst has obvious periods that was important for connecting productive reservoir.