The invention provides a method for simultaneously determining one hundred pesticide residuals in a traditional Chinese medicine through ultrahigh performance liquid chromatography-tandem quadrupole mass spectrum. The method comprises the following steps: immersing traditional Chinese medicine powder with ultrapure water, extracting with acetonitrile containing 0.1% acetic acid through a homogenate method, carrying out solid phase dispersing purification with N-propylethylenediamine and graphitized carbon, detecting in a timesharing multi-reaction monitoring mode through the ultrahigh performance liquid chromatography-tandem quadrupole mass spectrum, and quantifying with an external standard curve method. 88% of pesticides have good linear relations in a range of 5-500ng/mL, correlation coefficients are above 0.99, and the correlation coefficients of above 98% of the pesticides are above 0.97; the average recovery rate of the pesticides with the low concentration of 10mug/kg, the middle concentration of 50mug/kg and the high concentration of 100mug/kg is 70-130%, and the relative standard deviation is less than 0.15; and the detection limit is equal to or less than 0.01mg/kg, so routine detection requirements can be completely satisfied. The method has the advantages of strong versatility, good selectivity, high sensitivity, and rapidness and simplicity.