Ethrel is widely used as a stimulant in rubber tree plantations, which plays an important role in increaisng latex yield effectively and reducing labor requirements for tapping. However, the stimulatory effect of ethrel exhibits a pronounced dose-response relationship, excessive application may lead to adverse effects, such as tapping panel dryness (TPD). In this study, rubber tree clone Reyan 73397 was used as the experimental material, and an ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the trace determination of ethrel in the bark was developed. The distribution of ethrel at various time points and different parts of the bark following its application was investigated. The samples were extracted using a methanol∶1% formic acid aqueous solution (9∶1,V/V), and directly analyzed after filtration. The samples were separated by waters CORTECS HILIC C18 column (100 mm×2.1 mm, 1.6 μm) with mobile phase A (0.01% ammonia solution) and mobile phase B (acetonitrile∶water 80∶20, V/V) at a flow rate of 1.0 mL/min. The detection was performed under electrospray ion source, negative ion scanning and multiple reaction monitoring (MRM) mode. Quantitative analysis was conducted using external standard calibration curves, quantitative ion was 107. The results showed a good linear relationship for ethrel within the range of 0.02 μg/mL to 1.00 μg/mL, with coefficient of determination (R²) of 0.9997. Recoveries ranged from 85.3% to 101.2% at spiked levels 0.1 µg/kg to 1.0 µg/kg, with relative standard deviations of 1.14%-7.28%, and limits of quantification (LOQ) of 0.1 µg/kg. This method was applied to study the distribution characteristics of ethrel in stimulated bark rings, both above and below the ethrel-treated 5 cm and 10 cm areas, after applying different concentrations of ethrel (0.5%, 2.0%,4.0%) over 0-96 h. The results revealed that ethrel was unevenly distributed in the rubber tree, the concentration at the stimulated area was significantly higher than that in other areas, areas closer to the stimulated bark were higher than that in distant areas, and the areas below the stimulated bark were higher than that above it. The concentration of ethrel at the stimulated area showed a significant positive correlation with the stimulated ethrel concentration. Additionally, the concentration displayed an initial increase followed by a gradual decline over time. For the three concentrations, peak levels were observed between 12 h and 24 h post-stimulation, after which a gradual decrease occurred, with relatively high concentrations still detectable at 96 h. Compared to the indirect measurement of ethylene release rates by gas chromatography, this method has many significant advantages, including simplicity, rapidity, excellent reproducibility, and high sensitivity, thereby providing reliable technical support for the quantitative analysis of ethrel in rubber trees. The study preliminarily revealed the absorption, distribution and transport patterns of externally stimulated ethrel on rubber tree tapping cuts. It was found that the diffusion and transport of ethrel were limited, with the compound primarily concentrated at the stimulation site. The findings would provide a theoretical basis for further elucidating the dose-dependent effects of ethrel on yield stimulation and guiding its safe and efficient application.