Nitrogen fertilizer and planting density affect common buckwheat yield. The study used a common buckwheat cultivar to look at how different levels of nitrogen fertilizer and planting density impact leaf photosynthesis, plant traits, and grain yield. Results showed that grain yield increased with certain leaf characteristics and plant traits, reaching maximum values with 45 kg/ha of nitrogen fertilizer and 90 plants/m2 planting density. Plant height increased with nitrogen fertilizer but decreased with planting density. Overall, the combination of 45 kg/ha nitrogen fertilizer and 90 plants/m2 planting density is recommended for common buckwheat cultivation.