A new species of the avian Sapeornis is described based on a specimen discovered from the Early Cretaceous lacustrine Jiufotang Formation in Dapingfang, Chaoyang, Liaoning Province, Northeast China. The new species Sapeornis angustis is relatively small compared to the type species, S. chaoyangensis, and distinguishable from the latter in possessing 5-6 sacrals, a distinct narrow humeral deltopectoral crest with a less acute dorso-distal process, narrower furcular rami, a shorter hypocleidum, a relatively longer Metacarpal I and a shorter pubic symphysis. The discovery of a new species of Sapeornis provides more anatomical information about this basal avian, and documents the trend of size increase and some morphological specializations in its evolutionary history.