Researching the effects of different nitrogen fertilizer application rates and bio-fertilizer combinations on agronomic traits and yields of perennia tartary buckwheat, rice tartary buckwheat and common buckwheat. The suitable bio-fertilizer formula for each type of buckwheat were selected. The results showed that the application of biofertilizer on buckwheat had a substitution effect on nitrogen fertilizer. The 50% nitrogen fertilizer and bio-fertilizer treatment of rice tartary buckwheat can improve its quality and lodging resistance while ensuring the yield. The average yield perennial tartary buckwheat with 25% nitrogen fertilizer and bio-fertilizer reached 76.07 kg/667 m², more than 20% increase than control group. Under this treatment, the growth period of perennial tartary buckwheat was the shortest, the lodging resistance was enhanced, and the yield and efficiency were increased. There was no significant effect on the yield of common buckwheat treated with 75% nitrogen fertilizer and bio-fertilizer. However, the plant height was significantly reduced, the grain size was larger, and the 1 000-grain weight was significantly higher than the control group. It had been proved that applying suitable bio-fertilizer was one of the effective ways to promote the growth and development of buckwheat, improve the quality, increase the yield and reduce the application amount of nitrogen fertilizer. The research provided some references for the establishment of suitable buckwheat breeding technology system and green production technology model in Liaoning Province.