Based on the Cambisols of Beijing (used as agricultural soils), toxicity tests were conducted to investigate the effects of mercury (Hg) on reproduction and avoidance of Folsomia candida (Hexapoda: Collembola), as well as the transcriptional responses of the hsp70 gene, under different Hg concentrations and at different exposure times. Results showed that the hsp70 gene of the springtail was the most sensitive parameter to soil Hg stress, with a half-maximal effective concentration (EC50) of 0.42 mg/kg. The EC50 values based on reproduction and avoidance tests were 9.29 and 3.88 mg/kg, respectively. The expression level of the hsp70 gene was significantly up-regulated when soil Hg concentration was over 0.25 mg/kg (lowest-observed-effect concentration [LOEC]). In addition, responses of this gene expression were strongly induced after 48 h exposure under 1 mg/kg soil Hg, which probably was due to the fast and sensitive response of the gene transcription to Hg stress. Thus, the results suggested that the responses of the hsp70 gene and individual-level effects (reproduction and avoidance) could be integrated to provide helpful information for environmental monitoring and assessment of contaminated soils.