The disintegration of swelling rock when contacting with water is an important cause of engineering disasters, which is more obvious under the dry-wet cycles. The indoor disintegration tests were conducted on the swelling rock collected from Zhuzhou City, Hunan Province. Based on the concept of grading entropy, the relative base entropy of different dry temperatures, external disturbances and different initial mass of each block were studied. The results showed that, in the mode of static disintegration, the standard base entropy is the minimum at the dry temperature of 60 ℃ relative to that of 105 ℃ and 30 ℃. However, in the mode of disturbed disintegration, the standard base entropy of disintegration of swelling rock is almost unaffected by the drying temperature. Furthermore, in the case of constant temperature and initial mass of each block, the external disturbance has a significant effect on the standard base entropy of disintegration of swelling rock. The initial mass of each block has a certain influence on the standard base entropy of disintegration of the swelling rock, showing that the larger the initial mass of each block is, the smaller the standard base entropy will be. In addition, experimental studies have shown that the standard basic entropy is an important indicator to distinguish the strength of rock disintegration.