Abstract: 【Objective】 To provide a reference for the real-time monitoring of nitrogen nutrition and the scientific and rational application of nitrogen fertilizer during the key growth period of winter wheat under drip irrigation. 【Methods】 The leaf SPAD values of winter wheat under drip irrigation with different nitrogen gradients were obtained by using chlorophyll analyzer SPAD-502, the relationship among leaf SPAD value, nitrogen application amount and yield was analyzed, and the recommended nitrogen fertilizer model of winter wheat at each key growth stage based on SPAD value was established. 【Results】 Leaf SPAD value of drip irrigation winter wheat decreased slowly from jointing stage to booting stage, increased rapidly from booting stage to filling stage, and began to decrease after entering filling stage. The SPAD values of different nitrogen treatments were significantly different at different growth stages excluding milk maturity stage. There was a significant linear correlation between leaf SPAD and nitrogen application at jointing stage, booting stage, flowering stage and filling stage, and the correlation coefficient was above 0.826; The relationship between yield and nitrogen application was quadratic function,Y= -0.034,5X²+19.494X+6,035;The highest yield was 8,789 kg/hm², and the corresponding nitrogen application was 282.52 kg/hm², In order to obtain the optimal economic yield of 8,782.12 kg/hm², the nitrogen application amount was 268.67 kg/hm²; The critical SPAD values at jointing, booting, flowering and filling stages were 43.07、42.09、49.35 and 52.07, respectively. 【Conclusion】 A ideal nitrogen recommendation model was established according to the relationship between SPAD value and nitrogen application amount in each growth period.The recommended nitrogen fertilizer model based on SPAD value of wheat leaves can realize nutrient diagnosis and guide phased fertilization.