An extractant forced-circulation three-phase extraction (EC-TPE) device based on extraction-stripping coupling was developed for the preconcentration of Cd2+ in environmental samples. In this three-phase extraction (W1/O↔O/W2) system, Cd2+ in the sample solution (W1) was fully extracted into the stripping phase (W2) by the circular flow of an organic phase (O↔O). The extraction yield (EY) and enrichment factor (EF) reached almost 100% and 100, respectively, under the following operating conditions: 0.1 M HNO3, 2 mL/L di(2-ethylhexyl)phosphoric acid (P204), circulation flow rate of 32 mL/min, circulation time of 45 min and stirring speed of 400 rpm. An extraction yield of more than 98.5% was still achieved after reusing the organic phase eight times. Two theoretical formulas were established for predicting the EY and EF. Thereafter, EC-TPE was applied in the preconcentration of ppb-level Cd2+ for flame atomic absorption spectrophotometer assay with a detection limit of 0.17 μg/L. Addition/recovery tests for Cd2+ were carried out with recoveries exceeding 98%, and three environmental water samples were accurately analyzed. Finally, application of the EC-TPE device was extended to a different extraction system and other metal ions: Zn2+, Cu2+, Ni2+, and Co2+. The EC-TPE device is easily established utilizing common laboratory glassware, and the enrichment operation efficiency can be conveniently improved by using more than one device simultaneously.