The potential of online language learning has received much attention recently. This paper reports the design of an online writing system featuring learning support for non-native students during their writing process. The central premise is that in the online writing situation, students are in great need of writing aids. The proposed system provides a friendly and supportive writing environment. It consists of three main parts: writing practice, peer review, and e portfolio. Writing practice contains not only writing guidelines to raise students' consciousness of the structure of the target genre but also learning resources and tools that render full assistance. The resources include online translators, online dictionaries, phraseology, and wordlists, while the tools include a web concordancer and a collocation builder. Peer review allows students to give feedback to their partner's online writing, leading hopefully to reflection and revision. E portfolio consists of a learning record and a learning journal. Students can check their individual online writing record and retrieve both original and revised drafts for comparison. Learning journal is the place where students reflect over their writing process and problems. Pedagogical implications are finally discussed. (Contains 8 figures.)