Abstract: Pigai Network makes a comparison of differences between the corpus and the language used by students in their writing from multiple dimensions, and then presents the differences in the form of mark through cloud computing, and provides users with diagnostic feedback. Based on the theory of error analysis, 90 compositions submitted on the Pigai Network by those students from an independent college were analyzed. The result shows that there exist grammatical, lexical and textual errors, the reasons of which include non-linguistic, intralingual and interlingual factors.