Effect of some technical elements on seed yield and seed quality of the Cao Bang 1 and Bac Son tobacco varieties were initial studied at the Tobacco Economic and Technical Institute. Research results showed that the seed yield of the early spring season is higher than the middle spring season from 25 to 29 kg/ha and the weight of 1000 seeds of the early spring season is higher than the middle spring season from 3.0 to 3.7 mg. Planting density do not significantly effect on seed quality, but plays an important role in improving the seed yield. The seed yield of 16,500 plant/ha density is higher than the 14,000 plant/ha density from 20 to 22 kg/ha. Fertilizer and the amount of fruits are left on the plants have a significant effect on seed yield and seed quality. The seed yield of the 100 N - 200 P2O5 - 300 K2O fertilizer rate is higher than the 85 N 170 P2O5 - 255 K2O fertilizer rate from 11 to 14 kg/ha and the seed yield ofthe 85 N - 170 P2O5 - 255 K2O fertilizer rate is higher than the 70 N - 140 P2O5 - 210 K2O fertilizer rate from 10 to 15 kg/ha. The weight of 1000 seeds of the 100 N - 200 P2O5 - 300 K2O fertilizer rate is equivalent to the 85 N - 170 P2O5 - 255 K2O fertilizer rate and higher than the 70 N - 140 P2O5 - 210 K2O fertilizer rate from 3 to 5 mg. The seed yield of 120 fruit level is equivalent to the 100 fruit level and higher than the 80 fruit level from 37 to 40 kg/ha. However, the seed quality of 80 fruit level is equivalent to the 100 fruit level and higher than the 120 fruit level (about the weight of 1000 seeds from 9 to 13 mg
about the gennination rate from 11.0 to 12.8 percent).