What’s the meaning of rūpa-skandha? Different Buddhist sects have different opinions. The viewpoints of modern academia can be summed up into three categories. (1) rūpa-skandha is matter. (2) rūpa-skandha is the physical world experienced by a sentiment being. (3) rūpa-skandha is the property (or function) of matter. Because different historical periods and different Buddhist sects have different definitions of it, their basis can all be found in Buddhist literature. However, what is its initial meaning in the early Buddhist literature? No more detailed discussion has yet been made till now. Therefore, the paper will discuss this question and put forward the basis and reasons of interpretation. The common understanding of the various sects is as follows: rūpa-skandha is an accumulation of rūpa. But there are different interpretations of what rūpa means: one is “the four mahā-bhūta and the derivation of four mahā-bhūta”; one is “the four mahā-bhūta and the derivation of four mahā-bhūta related with sentiment being”. Through a survey of three aspects—the upper concept “five aggregates” of rūpa-skandha, the elements of rūpa-skandha, the definition of nāma-rūpa in the the twelve nidānas, a conclusion is drawn as follows: under the circumstance of early Buddhism, rūpa-skandha should be explained as “four great elements and derivation of the four great elements(rūpa) which is related with sentiment beings” . Therefore, rūpa-skandha can be defined as: one of “five aggregates”, an accumulations(aggregate) of four great elements and derivation of the four great elements(matter) which is related with sentiment being, its elements are eyes, ears, nose, tongue, body, rūpa, voice, fragrance, odor, tactile. Even if rūpa-skandha is defined in the early Buddhist documents, the explanation is still ambiguous, it need to be refined in some aspects, such as, whether rūpa exists in consciousness of sentiment beings or not, how to understand the relation between the consciousness and rūpa? The theoretical contradictions caused by the above questions are the key issues for Abhidharma and vijñapti-mātratā theory to solve.