Abstract: To expand the high-value utilization of rosin resources and identify lead compounds with in vitro inhibitory activity against phytopathogens, a series of dehydroabietyl 1,2,4-triazole-3-thione derivatives were synthesized and evaluated. Dehydroabietyl isothiocyanate was first prepared from dehydroabietylamine via reaction with carbon disulfide and N,N-dicyclohexylcarbodiimide, and was subsequently reacted with 16 substituted hydrazides to afford the corresponding dehydroabietyl acylthiosemicarbazides 3a-3p. Cyclization of these intermediates in 5% NaOH aqueous solution yielded 16 dehydroabietyl 1,2,4-triazole-3-thione derivatives 4a-4p in isolated yields of 50.9%-65.0%. The combined FTIR, ¹H NMR, ¹³C NMR, and HRMS data supported the proposed structures of the target compounds. Their in vitro inhibitory activities against Valsa mali, Phytophthora capsici, and Fusarium oxysporum f. sp. niveum were evaluated at 200 μg/mL using the mycelial growth rate method. The compounds exhibited markedly different inhibitory activities against the three tested phytopathogens. Compounds 4f and 4e showed inhibition rates of 57.69% and 56.92%, respectively, against V. mali, whereas 4a and 4d each inhibited P. capsici by 23.89%. Compound 4a showed an inhibition rate of 28.57% against F. oxysporum f. sp. niveum. Overall, only selected compounds exhibited moderate inhibitory activity against V. mali, while the series showed generally weak activity against P. capsici and F. oxysporum f. sp. niveum.