Apply the formative assessment and fuzzy mathematics into college English online learning evaluation

College English Curriculum Requirements demands that we should apply the formative assessment into students´ learning evaluation. This paper illustrates that the formative assessment theory and practice, then points out that the formative assessment is a much better assessment in language learning, and it can promote students´ language ability mostly, even students´ all round-development. Finally, this paper establishes an effective formative assessment index system of college English online learning and examines it with the fuzzy mathematics.