This chapter examines the development of Chinese syntactic complexity across global proficiency levels as well as the composition of individual terminable TC-units. L1 and L2 Chinese speakers’ spoken (N = 115) and written (N = 116) output elicited from a designed timed online test revealed significant correlations between complexity measures and proficiency scores, with varying patterns between global and clausal levels as well as between spoken and written Chinese. By checking such correlations displayed at global and clausal complexity levels, as well as along the length and ratio complexity measures, against the mean complexity scores by task across proficiency levels, this chapter confirmed the transition from subject- to topic-prominence of Chinese syntactic complexity (Jin, 2006). More importantly, this chapter further explores the dynamic nature of Chinese syntactic complexity development in terms of the transitional reliance from lengthening to combining single TC-units, the tradeoff between lengthening to combining single TC-units, and the varying developmental trajectories for spoken and written Chinese complexity.