To address the combined effects of cadmium (Cd) and elevated CO₂ on soil microbial communities, DGGE (denaturing gradient gel electrophoresis) profiles, respiration, carbon (C) and nitrogen (N) concentrations, loessial soils were exposed to four levels of Cd, i.e., 0 (Cd₀), 1.5 (Cd_1.5), 3.0 (Cd_3.0) and 6.0 (Cd_6.0) mg Cd kg⁻¹ soil, and two levels of CO₂, i.e., 360 (aCO₂) and 480 (eCO₂) ppm. Compared to Cd₀, Cd_1.5 increased fungal abundance but decreased bacterial abundance under both CO₂ levels, whilst Cd_3.0 and Cd_6.0 decreased both fungal and bacterial abundance. Profiles of DGGE revealed alteration of soil microbial communities under eCO₂. Soil respiration decreased with Cd concentrations and was greater under eCO₂ than under aCO₂. Soil total C and N were greater under higher Cd. These results suggest eCO₂ could stimulate, while Cd pollution could restrain microbial reproduction and C decomposition with the restraint effect alleviated by eCO₂.