The paper is proposed that the quality of age-specific population data declaration can be tested using difference sign of age-specific population structure and the variation of the difference between the data of a certain age group and the average of the two age groups flanking it,based on which the population of "age-heaping" and "age-eavading " in a certain age group can be estimated.

According to time and gap of the population growth rate,there are two kinds of demographic transition patterns-smooth and unsmooth,which discloses the relationship between demographic transition patterns and population multiplier.