Objective To compare the effects of modified platelet-rich fibrin (PRF) prepared under different centrifugation conditions in the treatment of severe chronic periodontitis. Methods Sixty-six patients with severe chronic periodontitis who underwent flap surgery in our hospital from September 2016 to September 2021 were selected as subjects. According to the preparation conditions of PRF, they were divided into low-speed preparation group (n=34) and high-speed preparation group (n=32). The modified PRF (A-PRF) was prepared by centrifugation at 1500 r/min for 14 min in the low-speed preparation group, and the modified PRF (L-PRF) was prepared by centrifugation at 3000 r/min for 5 min in the high-speed preparation group. The serum growth factor level, clinical attachment loss (CAL) and periodontal probing depth ( PD) were compared between the two groups after centrifugation. Results The levels of platelet-derived growth factor-BB (PDGF-BB), vascular endothelial growth factor (VEGF) and transforming growth factor-β (TGF-β) in the low-speed preparation group were higher than those in the highspeed preparation group (P<0.05). The levels of CLA and PD in the two groups at 3 months after operation were lower than those before operation, and those in the low-speed preparation group were lower than those in the high-speed preparation group (P<0.05). Conclusion The A-PRF obtained by reducing the relative centrifugal force and prolonging the preparation time is superior to L-PRF in terms of growth factor release performance, fibroblast proliferation and migration, and has high application value in promoting periodontal tissue regeneration and repair.