The purpose of the present paper is to study and develop indicators and procedures for the evaluation of genetic structure changes in plant germplasm conservation due to social and natural environment reasons. Some basic concepts in germplasm preservation were introduced at first. Then, six kinds of indicators for genetic diversity as a measure of genetic potential of a germplasm collection were presented, i.e. numbers of different entities at certain level, evenness of the entity distribution, genetic similarity and genetic distance, genetic variance and genetic coefficient of variation, multivariate genetic variation indices, and coefficient of parentage. It was pointed out that genetic dispersion did not provide a complete concept of genetic diversity if without any information from genetic richness. Based on the above, the indicators for genetic erosion as the genetic structure changes of germplasm conservation due to social reasons, the indicators of genetic vulnerability as the genetic structure changes of germplasm conservation due to environmental stresses, the measurement of genetic drift and genetic shift as the genetic structure changes of germplasm collection during reproduction or seed increase were reviewed and developed. Finally, the case studies on suitable conservation sample size of self-pollinated and open-pollinated populations were given for reference.