Objective: To get Eucommiae Cortex and salt-processed product of Eucommiae Cortex decoction pieces powder with optimum homogeneity by screening crushing process

in order to make them to be the standard reference materials. Method: According to microexamination and particle size distribution of Eucommiae Cortex and salt-processed product of Eucommiae Cortex decoction pieces in different grinding manners and the particle size distribution of control medicinal powder

ultrafine grinding was optimum grinding manner of them.Homogeneity of decoction pieces was compared by means of spectral difference

color and content of active ingredient. Result: Eucommiae Cortex and salt-processed product of Eucommiae Cortex decoction pieces powder was fine and had good fluidity when ultrafine grinding of 30 min

the spectral deviations of them were 0.002 and 0.001

RSDs of total color value were 0.5% and 0.4%

RSDs of pinoresinol diglucoside content of them were 2.3%. Conclusion: Ultrafine grinding of 30 min is the best grinding technology for Eucommiae Cortex and salt-processed product of Eucommiae Cortex decoction pieces

it provides a reference for formulating homogenization specifications of them.