Pine wilt disease is a serious condition affecting pine trees, with no known cure once infected. This study evaluated the preventative efficacy of injections of emamectin benzoate (95 g/L AL). Experiments were carried out in two locations in Taiwan in January 2024. Four groups were established at each site: Three groups of Pinus thunbergii Parl. were treated with varying dosages of emamectin benzoate (0.3, 0.7, 1.4 ml/cm DBH), while one group was the control. Three months after treatment, all groups of trees were inoculated with 10,000 pine wood nematodes. Symptoms of pine wilt disease were first observed in June 2024. The disease progressed rapidly during July and August of 2024. Disease incidence was evaluated seven months after inoculation. In Sanzhi District, incidence rates were 10%, 0%, and 0% for dosages of 0.3, 0.7, and 1.4 ml/cm DBH compared to 100% in the control group. In Emei Township, corresponding incidence rates were 50%, 10%, 10%, and 90% in the control group. Statistical analysis confirmed that tree trunk injection of 0.7 and 1.4 ml/cm DBH of emamectin benzoate (95 g/L AL) reduced the incidence of pine wilt disease, demonstrating significant preventive effect.