Nihewan basin is famous for its lacustrine deposits, animal fauna and occupied evidence of early humans. All of the discovered Palaeolithic sites are distributed along ancient lakeside or on the terraces of the Sangganhe river and its tributaries. However, the authors discovered a stone flake from the central part of the ancient Nihewan lake in an outcrop section on the right bank of the Sangganhe river. The location is 40°06′33″N and 114°20′15″E, near Jinerwa village, Yangyuan County, Heibei Province. The flake is basaltic and has a size of 4.5 cm×3.2 cm×1.7 cm. Its ventral surface is a fresh plane of fracture with a clear point of percussion,a bulb and a bulbar scar on it. The dorsal surface is composed of a residual part of a rounded pebble surface and a fresh plane formed along a joint. The flake is unearthed at 50.73 m under the lacustrine platform surface in perfectly laminated beds of Mid-Pleistocene. The feafures of the flake do not rule out the possibility of natural origin. But combined with the sedimentary features of the horizon where it is unearthed, the most reasonable explanation is that the flake may be the trace of ancient human activities on the frozen lake of Nihewan.