Abstract: Propamidine is an aromatic diamidine fungicide developed by our research group, with both protective and therapeutic effects, especially against gray mold. To reduce the field dosage and decelerate the development of fungicidal resistance of propamidine in treating gray mold, the combination of propamidine and fluxapyroxad were employed in aim to obtain synergistic effect, and formulated into water dispersible granule (WG). The optimal synergistic ratio of propamidine to fluxapyroxad was 1:4 (m/m), with a synergy ratio of 2.1359. Through single factor and orthogonal trials, the optimal formula for propamidine + fluxapyroxad 50% WG was finally determined to be propamidine 10%, fluxapyroxad 40%, AOS 2%, GY-D06 5%, sodium chloride 4%, and diatomiteto supplement to 100%. The quality test results of the formulation showed that the disintegration time of the WG was 30 seconds, the pH value was 4.8, and the suspension rate was 96.05%, all of which met the requirements. Greenhouse plot trials indicated that the formulation reached a curative effect of 54.06% at the active dosage of 400 µg/mL in treating severe gray mold disease (disease index 65.74), which was superior to the single dose of propamidine (49.30%) and fluxapyroxad (43.17%), respectively . It was also more potent than carbendazim at 1000 µg/mL (38.03%).