Material properties and hygroscopicity were determined. Principal component analysis and partial least squares regression were applied to evaluate relationships between material properties and hygroscopicity of Chinese medicine raw materials.  The results showed that hygroscopicity was correlated with water content, particle size distribution, water soluble characteristic and cohesion.  Balanced moisture content was positively correlated with water content, particle size distribution, water soluble characteristic    and cohesion.  Moisture absorption velocity was negatively correlated with particle size distribution, protruding degree and positively correlated with water soluble characteristic and cohesion.  Moisture absorption acceleration was positively correlated with water content, particle size distribution and negatively correlated with water soluble characteristic and cohesion.  Hygroscopicity of Chinese medicine raw materials is interpreted in terms of physics.