Abstract: In the actual system，i.e. in the acid solution after the nitric acid dissolving the phosphate rock，in a continuous mixed suspension mixed product removal（MSMPR） crystallizer at 19 ℃，the influences of different residence times on the crystallization kinetic parameters of calcium nitrate tetrahydrate were investigated and the correlation of the nucleation rate， suspension density，and growth rate was obtained，i.e.B0＝5.209 8×104MT1.056 3G1.109 4.Meanwhile，in the actual system，at 19 ℃，in 45 min，the effects of different stirring rates on the crystallization kinetic parameters of calcium nitrate tetrahydrate were investigated and the relationship was B0＝1.732 5×103MT1.037 1G1.021 3np0.606 6.The two formulas of actual system were contrasted with the ones of Ca（NO₃）₂-H₂O and Ca（NO₃）₂-H₃PO₄-HNO₃-H₂O systems in literature.The results had an important guiding significance to the actual industrial production.

Key words: phosphoric acid-nitric acid hydrolysis solution, calcium nitrate tetrahydrate, MSMPR crystallizer, crystallization kinetics