Wang Fuzhi suggests in Shuo Wen Guang Yi that modal particles all have their roots, and function words come from notional words; the terms he has used preliminary illustrate his classification awareness of function words sub-category; he pays more attention to documentary evidence when explaining function words; he discusses about the function words that hold two or more classes, and portrays the different usages of the same function word in detail; he attaches more attention to the comparison of function words of the same kind, and talks about the difference of the application of tone, which has the same effect as the research results of the ancient Chinese function words, and is worthy to be followed with interest by the academic circles.