This paper discusses the three issues in the Theory of Pratītyasamutpāda (interdependent origination) of Madhyamakaśāstra. Firstly, we point out that the central idea of Madhyamakaśāstra is pratītyasamutpāda, rather than satya-dvaya (the Two Truths). Secondly, as for the three kinds of contradictive interpretation of pratītyasamutpāda, we consider Candrakīrti's interpretation is more in line with the original idea of Nāgārjuna. Finally, we point out that the conception of pratītyasamutpāda of Madhyamakaśāstra has something to do with the importance of apekṣya (the property of referring to some other things). The universal definition of pratītyasamutpāda is that all things are mutually interrelated. Therefore, mutual interrelatedness is the true meaning of pratītyasamutpāda. Although this is not a semantic definition of pratītyasamutpāda, but it is more in line with the basic principle of pratītyasamutpāda: "When this is, that is; from the arising of this comes the arising of that," and the emptiness theory of Madhyamakaśāstra.