As for the meaning of “skandha”, different Buddhist sects have basically the same understanding, but they have different understandings to its theoretical annotation. In this regard, academic research is still insufficient. This paper compares and analyses their definitions of “skandha” based on three representative commentaries: Visuddhimagga, Abhidharma Mahāvibhāṣā Śāstra, Abhidharmakośabhāṣya, which belong to the Southern Sthaviravāda, Sarvāstivāda, taking both Sautrāntika and Sarvāstivāda respectively. The different understandings to “skandha” of the three commentaries are as follows: (1) There are different understandings of the specific elements constituting “skandha” between the Southern Sthaviravāda and the Northern Abhidharma teachings. (2) Regarding the nature of “skandha”, Abhidharma Mahāvibhāṣā Śāstra holds that it is “substantial existence”; Abhidharmakośabhāṣya holds that it is “nominal existence”; Visuddhimagga has no answer. There are three reasons for different understandings of the constituent elements of “skandha” : (1) The theoretical categories of the Southern Sthaviravāda are different from those of the Northern Abhidharma teachings. (2) The theoretical focus of the two sects is different: the former focuses on “skandha” while the latter focuses on “dharma”. (3) Their understandings and classifications of “conditioned phenomena” are different. The reason for different understandings of the nature of “skandha” lies in the following: Abhidharma Mahāvibhāṣā Śāstra emphasizes the common features of the “conditioned phenomena”, while Abhidharmakośabhāṣya emphasizes that “skandha” is an accumulation of different “conditioned phenomena”. Summarizing the points of the three commentaries, taking into account the Buddhist theoretical system, “skhanda” can be defined as nominal existence which is aggregated by all different conditioned phenomena which have intrinsic attributes, according to their common attributes