Abstract: Moyeam leaf spot caused by Diaporthe eres is an important fungal disease during the growth of vine tea, which significantly reduced the yield and quality of Moyeam. However, no fungicide was registered to control Moyeam leaf spot. In this study, the mycelial growth rate method was employed to determine the bioactivity of three triazole fungicides (difenoconazole, tebuconazole, and flusilazole) against D. eres. The study investigated the effects of the three fungicides on mycelial growth, hyphal morphology, and cell membrane permeability. Additionally, in vitro inoculation assays were conducted to evaluate their control efficacy against Moyeam leaf spot. The results showed that the three fungicides exhibited excellent antifungal activity, with the average EC₅₀ values of (0.17 ± 0.04), (0.37 ± 0.12), and (0.14 ± 0.08) mg/L, respectively. These fungicides were able to cause hyphal deformities of the D. eres, increase the permeability of the D. eres cell membrane, and cause electrolyte leakage inside the cell, but had no significant effect on the conidium germination rate. In addition, the three fungicides demonstrate exceptional efficacy in controlling D. eres under indoor conditions. At the concentration of 0.50 mg/L, difenoconazole, tebuconazole and flusilazole exhibited protective efficacy of 97.0%, 88.0% and 91.7% against D. eres under controlled conditions, respectively. The study demonstrates that these three triazole fungicides exhibit substantial bioactivity against D. eres, effectively inhibiting mycelial growth and disease infection. These results provide valuable references for the scientific control of Moyeam leaf spot.