Abstract: Biomass can be converted into high-value nitrogen-containing chemicals and nitrogen-containing carbon materials by pyrolysis technique, which significantly increases the value of biomass and lowers the risk of environmental pollution by nitrogen-containing pollutants. Therefore, a good understanding of the migration and conversion mechanisms of nitrogen during pyrolysis is critical for the advancement of biomass pyrolysis technique. Herein, the forms and contents of nitrogen in biomass were first summarized. Afterward, the transformation process of nitrogen from biomass to pyrolysis products was discussed based on the distribution of nitrogen in the solid, liquid, and gaseous pyrolysis products. Finally, the effects of fuel properties, pretreatment methods and pyrolysis conditions on the migration and transformation of nitrogen were discussed carefully. In addition, an outlook for future research on nitrogen migration in biomass pyrolysis process was provided.