Carbon capture and storage (CCS) is an effective technology to address climate change and achieve clean utilization of coal. However, high risk of CO₂ leakage from geo-structure still exists, which may pose a threat to farmland ecosystem and food security in China. Root growth is a unified process of interaction and mutual promotion between the upper and underground parts, and the morphological characteristics of root in soil has a great impact on crop productivity. However, the assessment on the effects of CCS leakage on plant roots is rarely reported. In this paper, maize was selected to reveal the response of crop to CO₂ leakage by pot experiment. Three treatments, CK (0 g m^-2 d^-1), G1000 (1000 g m^-2 d^-1), and G2000 (2000 g m^-2 d^-1) were designed to simulate different scenarios of CO₂ leakage by controlling flux of CO₂ at the bottom of pot. The results showed:CO₂ leakage had a significant effect on the root morphology of maize. The total root length decreased from 40290.81 cm to 21448.18 cm with increase of CO₂ leakage, reduced by 46.77%, of which the fine root decreased greatly. The yield of maize decreased significantly under CO₂ leakage treatments, the maximum yield reduction was 26.64%. The aboveground biomass was more sensitive than underground biomass under CO₂ leakage. With the increase of CO₂ leakage, there was a significant inhibition effect on the root development, aboveground biomass, underground biomass, and yield of maize. The responses of crop root morphology to CO₂ leakage provide scientific basis for CCS leakage monitoring and ecological restoration.