Based on daily meteorological data from 1998 to 2020 in Dongtai City, Jiangsu Province, FAO-recommended Penman-Monteith method and a single crop coefficient approach were applied to calculate the full growing season water requirement, effective precipitation and net irrigation water requirement for rice grown on non-saline and saline soils. The results showed that for non-saline soil with a total soil salt content below the rice salt tolerance threshold of 1.92 g/kg, the net irrigation water requirement for rice ranged from 301.0 mm to 594.7 mm, with a multi-year average of 446.3 mm, but for saline soil with a total salt content exceeding 1.92 g/kg, which ranged from 478.4 mm to 848.3 mm, with a multi-year average of 660.5 mm. If considering pre-planting leaching to suppress salt levels, the actual net irrigation water requirement would increase to 712.7-1 317.1 mm. The net irrigation water requirement for rice was highly variable from 1998 to 2020, with significant interannual fluctuations and a widening range of variation, indicating an increasing risk of drought and flood disasters, and also making it more challenging to predict net irrigation needs. The multi-year average water deficit index for rice was -0.68 for non-saline soil that do not require leaching, which was -0.77 for saline soil that do require leaching, indicating a significant water deficit and underscoring the need for enhanced regional irrigation system research.