It is obvious that the ordering distribution of temporal adverbial clauses in advanced Chinese EFL learners writing corpus (ACEFL) and English differs greatly. Based on the theory of dependency grammar, this paper builds two dependency treebanks and uses mean dependency distance (MDD) as an index to measure syntactic difficulty of prepositional and postpositional temporal adverbial clauses by advanced Chinese EFL learners. It is found that: 1) temporal adverbial clauses in Chinese show obvious tendency of preposition, while in English they can be preposed or postposed to the main clauses, but postposition is the dominant order. In contrast, advanced Chinese EFL learners tend to prepose temporal adverbial clauses which is similar to the ordering distribution of their mother tongue; 2) syntactic difficulty of prepositional temporal adverbial clauses in ACEFL is smaller than that of postpositional ones; 3) the main motivation of preposition of temporal adverbial clauses in ACEFL are dual influence of mother tongue and minimization tendency of MDD.