Onion is a main vegetable in panxi plateau of Sichuan province.but there were few reports on nutritional characteristics and fertilization technology of onion planting.Taking the locally onion varieties as the experimental materials，the effects on the absorption and utilization of nitrogen，phosphorus，potassium，yield and nitrogen utilization of onion were studied with different fertilization modes.The experiment set six treatments: PK，farmers' fertilization(NPK)(630-300-420)，optimized fertilization(540-270-330)，NPK+medium and micro fertilizer，organic fertilizer instead of 30% chemical fertilizer(70% CN+30% ON)，controlled-release mixed fertilizer(40% controlled-release N+60% conventional N).The results showed that the order of nutrient demand of onion in growth was nitrogen>potassium>phosphorus.The ratio of nitrogen，phosphorus (P2O5)and potassium(K2O) in onion was 8.4∶1∶7.8；For every 1000 kg onion produced，it absorbed 2.30～2.52 kg of N，0.57～0.69 kg of P2O5 and 2.45～2.84 kg of K2O.The highest yield，nitrogen apparent recovery rate，nitrogen partial productivity and agronomic efficiency of onion were ocurred in NPK+medium and micro fertilizer treatment，which increased by 8685 kg/hm²，17.06%，47.89 kg/kg and 24.96 kg/kg respectively compared with farmers' fertilization.The average yield，nitrogen apparent recovery rate，nitrogen partial productivity and agronomic efficiency of the three treatments(NPK，70% CN+30% ON and 40% controlled-release N+60% conventional N)increased by 7230 kg/hm²，10.1%，45.20 kg/kg and 22.27 kg/kg on average，respectively，compared with farmers' fertilization treatment.Therefore，it is suggested that priority should be given to the application of medium and trace element fertilizer，combined organic fertilizer instead of partly chemical fertilizer and controlled-release N based on the appropriate amount of N，P2O5 and K2O(510～540，240～270 and 300～330 kg/hm²)，so as to achieve the goal of reducing chemical fertilizer and increasing efficiency.