Based on the seismo-geological field investigation, a co-seismic surface rupture zone in Changlingshan area, Gansu province, was discoved recently. The rupture phenomena include： rock collapse, landslip, downthrown-pit, earthquake slot, uplift, scarplet, earthquake fissure and so on. The distribution of the rupture zone is controled strictly by Changlingshan Northern Piedmont Fault. Through the comprehensive research on the characters of the rupture zone, TL age testing, data of the regional active tectonics and the relationship between rupture zone lengths and earthquake magnitudes, it is considered that this rupture zone was caused by Gulang Ms 8.0 earthquake in 1927.