Objective To study the correlation between the particle size and cell -wall breaking ratio ,disso-lution rate of Zhichuanwu powder .Methods The particle size and cell breaking rate of four kinds of Chuanwu powder (40 mesh,60 mesh,80 mesh and 300 mesh) were determined by optical microscope .The dissolution characteristics of the above four kinds of powders were investigated by paddle method .Results The results showed that the particle size distribution,fracture rate and dissolution rate of the Chuanwu powder were different ,within 0-15 hours,with the increase of particle size of the prepared aconite root divided ,the dissolution rate increased from 81.2％ to 90.5％, and the cell breaking rate and dissolution rate increased with the decrease of the particle size .Conclusion Moderate changes in the degree of crushing can improve the rate of cell -wall breaking and rate of dissolution of active cells .