The subduction of the Paleo-Pacific Plate played an important role in the regional tectonic evolution of the eastern margin of the Eurasian continent, but the timing of this event remains ambiguous. To address this issue, this paper reports zircon U-Pb ages, zircon Hf isotopic compositions and petrogeochemical data of whole-rocks for the newly-found hornblende gabbro in Aohua Village, central Jilin Province. Zircon U-Pb dating shows that the hornblende gabbro was formed in Early Jurassic (180.3±2.3 Ma), and has high and uniform εHf(t) values (9.6~11.3). Petrogeochemical analyses show that the samples are characterized by low Si and Al, and high Fe, Mg, and Ca, enrichment of light rare earth elements and large-ion lithophile elements (e.g., Rb, Ba, U, K, and Sr), and depletion of heavy rare earth elements and high-field-strength elements (e.g., Nb, Ta, and Ti), and have weak negative Eu anomalies (δEu=0.67~0.98). They were derived from a depleted lithospheric mantle source that had previously been metasomatized by slab-derived fluids, with unapparent effects of fractional crystallization, crustal contamination and cumulation in the formation process. Combined with rock associations and spatial distri- bution of Early Mesozoic igneous rocks in the eastern part of Northeast China, the authors hold that the subduction of the Paleo-Pacific Plate beneath the Eurasian continent started in Early Jurassic, and the hornblende gabbro was formed in the back-arc setting which might have been closely related to the subduction of the Paleo-Pacific Plate.