OBJECTIVE： To establish a method for the determination of 100 pesticide residues in Morus alba. METHODS： LC-MS/MS was conducted on the column of ZORBAX Eclipse plus C18 with mobile phase of acetonitrile （containing 5％ water， 0.1％ formic acid， 5 mmol/L ammonium formate） - water （containing 0.1％ formic acid， 5 mmol/L ammonium formate） （gradient elution） at a flow rate of 0.4 ml/min， column temperature was 40 ℃， injection volume was 5 μl； MS conditions： ionization source was electrospray ionization with positive ion mode， scanning mode was dynamic MRM， scanning time window was 2 min； atomizing gas was nitrogen， atomizing gas pressure was 40 psi， drying gas flow rate was 5 L/min， capillary voltage was 4 000 V， and ion spray voltage was 500 V. RESULTS： The linear range of 100 pesticide residues was 2.4-150 ng/ml （r＞0.990 0）， recovery was 69.3％-128.2％， and the determination limit was 0.003-16 μg/kg. CONCLUSIONS： The method is simple， stable and reproducible， and can be used for the determination of pesticide residues in M. alba.