<p>The ash aggregates occur in the pyroclastic rocks of Early Cretaceous Yingcheng Formation, which are outcropped in the southeastern margin of the Songliao Basin, China. We focus on the types and genesis of the ash aggregates. Five types of ash aggregates are identified, including ash pellets (Ap), layered accretionary lapilli (Lacc), ultrafine rim-type accretionary lapilli (Ufacc), coated lava particle (Clp), and coated breccia (Cb), and there are six types of lithofacies related to ash aggregate accumulation: (1) Ap and Lacc bearing fine tuff with hummocky-parallel bedding, (2) Ufacc bearing fine tuff with hummocky-parallel bedding, (3) Lacc and Ufacc bearing fine tuff with hummocky-parallel bedding, (4) Ap, Clp, Lacc, and Ufacc bearing medium-fine tuff with graded and parallel bedding, (5) Lacc and Cb bearing lapilli-ash tuff with massive-graded bedding, and (6) Cb bearing lapilli tuff with massive-welded structure. Base surges, pyroclastic flows, and ash falls contribute to the ash aggregation, especially ash falls. Our study of the ash aggregate accumulation relative to the lithofacies and their spatial distribution is helpful to reconstruct the paleo-volcano edifice, distinguish the ash fall deposits from the pyroclastic flow/surge deposits and infer wind direction during the time of volcanic activity in the research area.</p>