In this study,genetic stability of foreign genes was checked by using PCR technology. A total of 4 lines of soil samples from transgenic and non-transgenic control Populus alba×P.glandulosa and the soil samples from the stands were collected in two successive years,and the bacteria,fungi and antinomyces were isolated by using flat dilution method to determine their quantities. The results demonstrated that target genes were stable present in the genome of transgenic poplar. We found that three kinds of soil microorganism appeared different trends within different months and different years. The ANOVA and multiple comparison analyses revealed that there was no significant difference in quantity of the soil microorganisms among most poplar lines at the same time point. Meanwhile,significant differences of the soil microorganism community were found among several transgenic lines,and between a few transgenic and non-transgenic lines,but they did not show any relation to the type and number of foreign genes. Our preliminary results indicated that the 2-year-old transgenic poplar growing in field had no significant effects on soil microorganisms.