With Cangshan garlic and early bolting garlic as experimental materials, this paper studies the effect of nitrogen topdressing on the garlic growth and yield of garlic stems and garlic bulbs. The results show that under the same amount of nitrogen, applying ammonium phosphor nitrate can better promote the growth of garlic than applying urea and ammonium chloride; both ammonium chloride and ammonium phosphor nitrate can effectively improve the yield of garlic stems and garlic bulbs, especially for ammonium phosphor nitrate; through economic benefit analysis, applying ammonium chloride and ammonium phosphor nitrate can produce greater economic benefits than applying urea, and especially ammonium phosphor nitrate increases the economic benefits of Cangshan garlic and early bolting garlic by 5490 yuan and 6690 yuan per ha, respectively.