The influences of Fe3+，Al3+，F-，SO42-ions on the crystallization process of ammonium dihydrogen phosphate(MAP) were studied by means of batch crystallization process.The results showed that the dopant of Fe3+，Al3+ had siginificate effect on MAP crystallization process, which made the crystal shape changeing from prism to spiculate; with the increase of dopant, the metastable zone width(MZW) increased, the crystallization induction period increased obviously, the crystal growth rate decreased and the average crystal size decreased; With the increase of Mg2+, the metastable zone width widened, the average crystal size and l∶ddecreased; The existence of F- widened the metastable zone, minished the ratio of length to diameter of crystal.shape changed the crystal from long prism to short prism;The effect of SO42- on crystallization process was neglectable. The experiment results are quite valuable to MAP production.
