A pot experiment was conducted to determine the effects of four treatments, i.e., CK (neither urea nor vermicompost was applied), CF (100% of nitrogen was provided by urea), VC (100% of nitrogen was provided by vermicompost), and VC+CF (two 50% of nitrogen were provided by vermicompost and urea, respectively), on the soil microorganism population, enzyme activities, root construction and physiochemical properties in rhizosphere soil of poplar seedlings. Results showed that the VC+CF treatment was beneficial to coordinate the soil C/N ratio, and the application of inorganic fertilizer could supplement the consumption of nitrogen in the soil. Besides, the microorganism population and the activities of urease enzyme, catalase enzyme, polyphenol oxidase enzyme and invertase enzyme significantly increased. As compared with the CK, CF and VC treatments, the bacteria population in the VC+CF treatment increased by 165.99%, 67.34% and 31.73%, and the invertase enzyme increased by 90.37%, 45.31% and 32.34%, respectively. Vermicompost application had a beneficial effect on the fine root growth, and the aerial part was influenced by vermicompost greater than the under-ground part. Additionally, the VC+CF treatment obviously reduced soil pH value and significantly enhanced the efficiency of nutrient ions in the rhizosphere soil. Compared with the VC+CF treatment, the VC treatment had little effect on soil biological characteristics of one-year poplar seedlings. vermicompost co-applied with inorganic fertilizer had better effect on ecological environment in rhizosphere soil of poplar seedlings.