Cadmium (Cd) and arsenic (As) are the most significant combined pollutants in the soil of the major rice-growing areas in southern China. Although the gene editing technology targeting OsNRAMP5 can significantly reduce the accumulation of Cd in rice grains, its effect on As is still unclear. In this study, 10 low-Cd accumulation rice varieties were selected as the research subjects and experiments were conducted in Cd-As co-contaminated paddy soil. The As concentrations in 14 parts such as grains, roots, nodes, internodes and leaves were systematically measured, and the As transport coefficients between nodes, leaves and grains and their correlations with grain As accumulation were analyzed. The results showed: (1) The As concentration in the grains of the tested varieties ranged from 798 to 1703 μg/kg, with the OsNRAMP5 knockout variety LCD1 having the highest (1703 μg/kg), and the high-Cd accumulation variety YYW3 being lower (1065 μg/kg), and there was a significant negative correlation between Cd and As in rice grains; (2) The As concentration in nodes was strongly negatively correlated with the transport coefficient, and the upward transport efficiency of As could be reduced by retaining As; (3) Although the LCD1 variety could efficiently reduce Cd (18 μg/kg), its As concentration in nodes and the node-leaf transport coefficient were at a relatively high level. This study suggests that knocking out OsNRAMP5 may trigger a metabolic compensation effect by up-regulating the expression of As transport-related genes, and the promotion of a single low-Cd variety in Cd-As co-contaminated soil may pose a potential health risk of As accumulation. The research results provide strategic support for the safe production of rice in co-contaminated farmland.