Parameter setting and testing conditions have a direct impact on text reasults of Coulter Multisizer3 particle-size analyzer.Electrolyte NaCl concentration,current and gain,test time,test volume and particle number were used as the research factors,and particle size value was used as the research index.Experimental results show that with the increase of NaCl electrolyte concentration,the average particle size value increases,it is most close to the standard values at 0.9%.As gain increases and current decreases,the average particle size value first increases then decreases,and has a max value at -1 600×2,preferred value at -800×4.With increasing time of test, the average particle size value increase before it becomes stable,and it is most close to the standard values at 60 s. Test volume is correlated negatively with the average particle size value selecting -1 000 μL.Meanwhile with increasing number of test particle, the average grain size decrease as a whole and it has a preferred value 20 000. Mode is relatively stable and only the change of current and gain affect its numerical changes.