On the basis of the quantitative analysis and qualitative analysis, this paper has chosen eleven classic works which represent the ancient language features in pre-Qin period. It has analysed ＂Er＂ in them one by one and has made an explicit survey and statistics about the usage of ＂Er＂. Meanwhile, the paper has tidied up the grammatical function of ＂Er＂ as second person pronoun.