The fifth national population census held in November 2000 is the first population census in socialist marketing economy system .Comprehensive and deep changes in the society present the population census with big challenges .Many people have noticed the possible difficulties the census will encounter and some opinions from scholars have been published in a previous forum in the 6th issue of Population Research in 1999 , which came to the conclusion that it is rather hard to obtain an accurate data in the 2000 census .The conclusion was confirmed in the process of the census .It can be anticipated that with the perfection of the marketing economy system and the enhancement of people' s awareness about privacy , many problems will continue to keep and emerge in the future surveys and censuses. Considering that , this forum invites opinions from four scholars on this topic .