Abstract: Formulaic sequences could be advantaged by the L2 learners to achieve fluency and idiomaticity in writing. In an attempt to better understand the longitudinal development of formulaic language in English writing, especially in the Chinese context, we followed a group of five Chinese non-English major college students and analyzed all the writing assignments. The research finds out that the subjects' awareness, appropriateness and confidence of using lexical bundles are enhanced to a certain degree, while the quantity and diversity of using lexical bundles are unstably changed. Based on those findings, some suggestions on English writing instruction are made for intermediate English learner, which includes enhancing the training on the awareness of using formulaic sequences, improving the implicit strategies of learning formulaic sequences, and requiring a model of free writing with formulaic sequences.