In order to clarify the effects of reducing nitrogen application on soil inorganic nitrogen and nitrogen accumulation in tobacco plants under drip fertigation, a field experiment was carried out in 2016 in Dengfeng of Henan Province, which included five treatments: T0, no nitrogen fertilization; T1, conventional fertilization; T2, 15% reduction of nitrogen; T3, 30% reduction of nitrogen; T4, 45% reduction of nitrogen. Inorganic nitrogen contents in 0-20, 20-40 and 40-60 cm soils and nitrogen accumulation in tobacco plants were analyzed. The correlation was analyzed between the characteristics values of fitting curves of inorganic nitrogen in 0-20 cm soil and nitrogen accumulation in tobacco plant. The results showed that drip fertigation could significantly increase inorganic nitrogen in 0-20 cm soil in 40 and 50 days after planting and significantly reduce soil inorganic nitrogen in 40-60 cm soil in 50 days. 15%-30% reduction of nitrogen had no significant effect on the yield of tobacco leaves and on the nitrogen accumulation in tobacco plants, but the yield and nitrogen accumulation in tobacco leaves and plant decreased significantly by 11.52%, 45%, 10.53% and 10.50% respectively under 45% reduction of nitrogen. Nitrogen agronomic efficiency (NAE) and nitrogen partial factor productivity (NPFP) were the highest in T4, and gradually decreased with the increase of nitrogen rate. Apparent recovery efficiency (ARE) of nitrogen fertilizer was the highest in T3. Nitrogen harvest index (NHI) and nitrogen physiological efficiency (NPE) had no obvious correlation with nitrogen rate. However, the decrease of nitrogen rate could prolong the decrease duration of inorganic nitrogen and the rapid growth stage of tobacco plants, and reduce the maximum decrease rate of inorganic nitrogen and the maximum nitrogen accumulation rate of tobacco plants, which is adverse to the rapid accumulation of nitrogen in tobacco plants. Therefore, it is considered that reducing nitrogen by 15%-30% under drip fertigation is beneficial to the efficient utilization of nitrogen fertilizer in this study region.