The monosodium glutamate solutions with different viscosity gradient was prepared by different concentrations of sucrose solution.The effect of viscosity on glutamic acid crystal habit and particle size distribution was investigated in this study.Meanwhile,the effect mechanism of viscosity on glumatamic acid crystallization was also probed through measuring glutamate induced crystallization time and the changing of growth rate at different viscosity.Experimental results showed that the viscosity has no effect on the crystal habit of glutamate in the measured viscosity range(1.00~10.30 mP·s).At the same supersaturation,the increasing of the viscosity resulted in the prolong of the crystallization induction time of glutamate,the decrease of the rates of crystal nucleation and crystal growth.Consequently,the particle diameter of glutamic acid crystals was decreased,while the uniformity of crystal size was slightly increased.Therefore,through appropriately improving the crystallization temperature in industrial production,the reducing of the viscosity of the solution could result in the shorten of the crystallization inducing time and improvement of the crystal growth rate,and ultimately making it more conducive to the crystallization of glutamic acid.