Abstract: Clause combining (CC) has received remarkable attention from linguists in recent years.Based on the canonical tripartite division of complex sentences, western linguists proposed a cline of clause combining as ‘coordination > cosubordination > subordination’.Through a detailed investigation of the cosubordinate complex sentences, this paper proposes a further division of cosubordination into bidirectional (cosubordination I) vs.mono-directional (cosubordination Ⅱ) dependence; therefore, the paradigm becomes ‘coordination > cosubordination Ⅱ > cosubordination I > subordination’.Instead of treating CC and grammaticalization as if they were blended, just as has been the case of most existing traditional researches, this paper regards the dynamic procedures of CC as the structural grammaticalization of clauses during which the lexical-to-grammatical or grammatical-to-more-grammatical evolutions are highly likely to co-occur.Finally,the paper also provides some comments about the CC researches by Chinese grammarians and proposes future research directions.