In order to expand exploration space of Sha3 igneous in eastern sag, Liaohe depression, using core observation, thin-section analysis, seismic and logging methods, genesis and reservoir characteristics of igneous rock were studied thoroughly in Sha3 member in eastern sag. The results show that the igneous develops well in the layer of that area, presenting beaded distribution along faults and multi-stage superimposed. The major three rock types are lava, vein rock and pyroclastic rock. Volcanic erupted following the fissure pattern and igneous mainly distributed in the downthrown of faults. The major petrographic types are outbreak, overflow and volcanic sedimentary facies. Among them, the outbreak facies are the most favorable ones for igneous exploration. Main faults control igneous formation mechanism. The igneous rock belongs to fracture-pore type reservoir and its reservoir property is controlled by the factors of structural fracture, igneous lithology and lithofacies. Comprehensive evaluation shows that the igneous in the study area is characteristic of widespread distribution in horizontal, multi-stage superposition in vertical, and adjacent to the deep source rocks in lateral. It is favorable for the formation of complex reservoirs and also is the key target area for deep igneous exploration.