Based on the comparison of the relevant articles of runoff series in the five hydrological calculation codes issued successively since 1983, this paper analyzes the relevant articles of the current codes (as the representatives of the last four codes). Under the condition that the runoff series is long, several series representativeness analysis and evaluation methods recommended by the current standard still need to be studied and perfected. The principle of comparing the method with the reference station with longer series is still advocated as the basic method of series representativeness analysis and evaluation is still adopted. Based on this, some suggestions are given to amend relevant provisions of the code. The paper puts forward some tentative ideas to further improve the problem.