Abstract: An ultra high performance liquid chromatography-tandem mass spectrometry method was developed to study the dissipation dynamics and final residues of 2,4-D in Musa paradisiaca. The M. paradisiaca samples were extracted by acetonitrile, salted out and stratified by sodium chloride. Using negative ion ionization and multiple reaction monitoring, the results showed that there was a good linear relationship between the concentrations of 2,4-D and the corresponding peak area in the range of 1.0 μg/L to 10 μg/L. The limits of detection and quantification of the method were 0.001 5 mg/kg and 0.005 mg/kg, respectively. The average recoveries was in the range of 93% to 99% with the relative standard deviations from 2.5% to 3.0% at three spiked levels of 0.005, 0.05 and 0.5 mg/kg. The method is suitable for the 2,4-D residues detection in M. paradisiaca. The results of field experiments show that the half-life of 2,4-D was 5.4 days, indicating that 2,4-D is a non-persistent and easily degradable pesticide. The final residue test results showed that 2,4-D was LOQ in the M. paradisiaca 60 days after harvest, at dosages of of 23, 35 and 53 mg/kg (effective component concentration), respectively.