At present, the research on the electrochemical reduction of CO₂ (ECR-CO₂) mainly focuses on the electrode material and the catalyst. However few studies involved the reactor and reaction conditions. In this study, the commerical available nano-Sn catalyst was coated on a gas diffusion electrode to form a working electrode (Sn/GDE), the influeces of distance between the aonde and the cathode were systematically investigated in a reactor for ECR-CO₂. The experiments show that for the electrode distance chnaged from 1.5 cm to 5.7 cm, both current density and Faradaic efficiency were decreased sharply from 34.6 to 10.4 mA cm^-2 and 80% to 60%, respectively. However, the distance of 3.3 cm seems to be a critical point, at which the current density was no longer changed.