Abstract: This study is meant to provide a generative syntactic account of the Chinese aspect marker qilai.As a starting point, a cartographic investigation of the aspectual system is carried out based on previous studies.It is proposed that the notion of aspect can be classified into four levels, i.eJP10.JP, situational aspect, phasal aspect, viewpoint aspect and perspectival aspect, each realized at its specific levels of syntactic derivation and fulfilling different grammatical functions.Based on this view of the aspectual domain, the authors present their view regarding the syntactic status of qilai and the derivational processes of constructions containing it.It is argued that qilai is not a simple aspect marker.Rather, it is composed of two aspectual markers, with qi and lai functioning as phasal and viewpoint aspect heads respectively.Cases where an object nominal occurs between qi and lai are derived in the same way as those where qi and lai are adjacent to each other, both involving head-lowering and clticizing.It is also demonstrated that the co-occurrence constraints between qilai and other aspect markers can also be accounted for with the proposed analysis.