Syntactic complexity is the complexity and Variability of sentence structure in second language writings （L2 writings）. It has been considered one of the major indicators measuring L2 writings. This paper reviews and com- pares the parameters, indicators and research findings of syntactic complexity in China and other countries, and finds that there are still many problems with the current research in this area - - the confused classification and application of indi- cators, the calculation of indicators; which indicators can best measure L2 learners＇language level; the relationship a- mong indicators; the validity of indicators.