This study investigated Chinese learners with French as a third language (N = 121). Six language tests, including English morphological awareness, French morphological awareness, English-French cognate awareness,French vocabulary breadth and depth, as well as French reading comprehension, were administered separately. Through path analysis, the effect of morphological awareness on vocabulary and reading comprehension within the third language (French)and across English-French were explored respectively. The results revealed that English morphological awareness was transferable to French vocabulary knowledge by influencing French vocabulary depth and English-French cognate awareness. This study confirmed the transferability of morphological awareness even in third language acquisition.