In the process of batch isoelectric point crystallizaton of L-glutamic acid,the crystal size distribution(CSD) will be directly influenced by addition of crystal seeds.This work aims to determine the optimal conditions for seeding operations.Effects on crystallization are studied by adding seeds with different surface area and different average size.Results show that the CSD can be controlled if the seed surface area reaches critical surface value(Sc).When the average seed size ranged from 67.3 μm to 91.9 μm,the Sc was not more than 50 cm2,and the corresponding Sc was 100 cm2 for the region of 103.7 μm to 117.7 μm,and the corresponding Sc was 250 cm2 for the average seed size of 154.8 μm.When the average seed size beyond the 235.9 μm,the CSD of the final product are bimodal.As for the seed size,at the same seed surface area,the seeds with larger size have higher crushing rate and lower absorption rate for solutes,thus have greater critical surface value.