Abstract: The delamination of high-purity Na-montmorillonite was studied by different combinations of low-speed stirring, ultrasonic action, high-speed stirring and addition of delaminating agent. XRD and XRF were used to analyze the phase and chemical composition of the samples. Thermal field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to characterize the apparent morphology and particle size of the samples. The results showed that the effect of ultrasonic action was superior to that of high-speed stirring. The addition of dispersing agent sodium hexametaphosphate was beneficial to the delamination of montmorillonite. Under the experimental conditions, the high-purity sodium montmorillonite slurry with mass concentration of 2.5% was stirred at low speed for 30 min after 30 min ultrasonic treatment, and then to be stirred at high speed for 30 min, so the best delaminating effect was got at last.