【Objective】Elevated near-surface ozone (O3) concentrations are an increasing threat to rice production, but the mechanisms and dose effects on below-ground ecosystems, including soil nutrient cycling and microbial communities, remain poorly understood. 【Method】This study targeted three major rice cultivars (HuaiDao 5, NanJing 5055, and WuYunJing 27) in the Yangtze River Delta. Using open-top chambers, we conducted an 84-day fumigation experiment with four ozone concentration gradients, including [NF (ambient air), NF20 (ambient air + 20 nmol·mol-1 O3), NF40 (ambient air + 40 nmol·mol-1 O3), and NF60 (ambient air + 60 nmol·mol-1 O3)], to systematically analyze the dose-response effects of elevated O3 concentration on soil nutrients and microbial communities in paddy fields. 【Results】The results showed that increasing O3 concentration significantly altered soil NO3--N and available phosphorus (AP) contents, as well as the abundances of methanotrophs (pmoA gene) and archaea during the rice filling stage, whereas no significant effects were observed for soil DOC, total carbon (TC), available potassium (AK), bacterial or methanogen (mcrA gene) abundances. The interaction between O₃ fumigation and rice cultivar significantly affected soil NH4⁺-N, NO3⁻-N, and AP contents. Specifically, O3 fumigation significantly reduced NO3⁻-N contents in HuaiDao 5 and WuYunJing 27, although the inhibitory effect weakened with increasing O3 concentration. In contrast, NH4⁺-N content in NanJing 5055 significantly increased under the highest O3 treatment (NF60). Similarly, NH4⁺-N in HuaiDao 5 decreased under O3 stress but the effect weakened at higher concentrations, whereas NH4⁺-N in WuYunJing 27 increased under NF60. AP content in HuaiDao 5 exhibited a negative correlation with O3 concentration, whereas no significant effects were observed in the other two cultivars. O3 fumigation significantly increased the abundance of pmoA gene in NanJing 5055 and WuYunJing 27, with the promoting effect intensifying under higher O3 concentrations. Soil bacterial community analysis revealed cultivar-specific responses, the relative abundance of Bacteroidota in WuYunJing 27 and Chloroflexi in NanJing 5055 was positively correlated with O3 concentration, while the relative abundance of Bacteroidota in NanJing 5055 and Desulfobacterota in HuaiDao 5 showed significant negative correlations. Moreover, the abundance of carbon and nitrogen metabolic pathways in NanJing 5055 and WuYunJing 27 exhibited nonlinear dose-response relationships with increasing O3 concentrations. 【Conclusion】Our findings demonstrate that soil nutrient dynamics and microbial community responses to O3 stress are highly cultivar-specific, with evidence suggesting the existence of threshold concentrations for O3 sensitivity. However, accurately quantifying the mechanisms underlying O3-induced alterations in below-ground elemental cycling and identifying key ecological thresholds will require long-term in situ observations. These findings offer critical insights for assessing the ecological risks of ozone pollution in rice paddies and guiding the selection of ozone-tolerant cultivars.