The invention relates to a coring device for petroleum geology, which is composed of a main body component, a coring inner barrel component, a drilling inner barrel component and a coring drill bit component; the main body component comprises a main body and a latch lock; the coring inner barrel component comprises a fishing head, a suspension joint, a bolt pin, a thrust bearing, a pressure relief joint, a coring inner barrel, a core catcher sub and a core catcher; the drilling inner barrel component comprises a fishing head, a suspension joint, a bolt pin, a diverting joint, a drilling innerbarrel, a gamma measuring device and a drill bit plug; and the coring drill bit component comprises a coring drill bit and an alignment bearing. When in use, the coring device is connected under the drilling string, and when the coring device approaches to the position of the coring layer according to the prediction, the main body of the device, and the coring drill bit and the drilling inner barrel component are tripped in, so as to form comprehensive drilling;, when the coring device reaches the position of the coring layer, the coring operation can be carried out by rapidly replacing the coring inner barrel component through a rope fisher, thereby avoiding the tripping operation, and greatly reducing the risk of the coring operation.