Abstract: In this article, the effect of nitrogen application and planting densities on agronomic character and output of Hongda in the field is researched, and we also measured the difference of light intensity and temperature during different groups. The results showed that leaf area index is preliminary mainly affected by the amount of nitrogen with the advance of growth period, planting density became more important. In Rosette period, light intensity of the base weakened with the increase of nitrogen application and planting densities. But the interaction of nitrogen application and planting densities in Flattened period on the lower, middle parts are clear differences. Temperature changes in different vertical height with the increase of nitrogen, smaller nitrogen application, more drastic temperature changed. In Vigorous period, at 14, the highest temperature in tobacco fields appeared the canopy which was 65 cm height from the ground, other times increased with a vertical height increased At low nitrogen level, increasing planting density could get a higher output, and at high nitrogen level, increasing planting density did not increase the output, but declined in the quality of tobacco. Comprehensively, 5 kg nitrogen and 1,330 strains per 666.7 m2 can reap a best productivity.