OBJECTIVE： To establish a method for simultaneous determination of 18 toxic elements from 10 ingredients of Modified xiaoyao formula and their extracts， and to study transport rates of above elements. METHODS： Microwave digestion-inductively coupled plasma mass （ICP-MS） was used to determine above elements. Radio-frequency power was 1.50 kW， atomization pressure was 720 kPa， sampling depth was 7 mm， plasma gas flow rate was 15.0 L/min， carrier gas flow rate was 1.00 L/min，spray chamber temperature was 2 ℃， He flow rate was 4.5 mL/min under collision mode， measurement points/peak was 3， data acquisition mode was jump mode. RESULTS： The linear ranges of As， Pb， Cu， Hg， Cd， Mo， V， Cr， Mn， Fe， Ni， Zn， Ru， Rh， Pd， Os， Ir， Pt was 0-500.17 ppb（r was 0.999 4-0999 9）； LOD was 0.000 4-5.341 0 ng/g； RSD of repeatability tests was all lower than 5.0％； average recoveries were 82.0％-117.9％ （RSD＝0.2％-5.7％，n＝9）. Ru， Rh， Pd， Os， Ir， Pt， Hg had not been detected. The transfer rates of 11 metals in the extracts ranged 1.46％-31.90％. CONCLUSIONS： The method is simple， precise， stable and repeatable， and can be used for simultaneous determination of 18 toxic elements in 10 ingredients of Modified xiaoyao formula and their extracts. The contents of toxic elements are decreased during the preparation of Modified xiaoyao formula extract to guarantee the safety of drug use to certain extent.