Abstract: A sample cell was specially designed and improved for studying crystal growth of lysozyme using vapor diffusion approach by dynamic light scattering.Various rates of vapor diffusion can be easily achieved by adjusting the concentration of the precipitator.A series of experiments using 1,3 and 4 mol•L－1 NaCl solution and silica gel particles as precipitator were performed and lead us to the conclusion that the rate of vapor diffusion was of great importance for controlling crystal growth.For higher precipitator concentrations (3,4 mol•L－1 NaCl solutions and silica gel particles),the sizes of particles in the initial stage fluctuate very considerably,while it was not the case for lower concentrations (1 mol•L－1 NaCl solution).During the nucleation stage,the time period decreased with the increasing concentration of the precipitator,but the diameters of particles remained at about 4～6 nm in despite of different rates of vapor diffusion.This shows that the rate of forming supersaturation plays an important role in crystal growth process.