The research on the geometric structure and kinematic characteristics of the ends of earthquake surface ruptures is helpful to understand the fracture propagation and termination process scientifically. The Xiadian fault is a crucial seismogenic structure in the North China Plain, where occurred the Sanhe-Pinggu M8 earthquake in 1679. So far, the length of its co-seismic surface fracture and the deformation characteristics of its ending parts remains controversial. Based on the results of previous study and field geological survey, two shallow seismic exploration profiles were arranged at the end of the surface rupture of the 1679 Sanhe-Pinggu M8 earthquake, and the new activity characteristics at the end of the fault were studied. The results showed that the latest activity at the end of the fault occurred in the Holocene. The movement mode is mainly strike slip with a normal slip component, showing obvious characteristics of slip deficit. Combined with the data of co-seismic vertical displacement distribution, it is considered that the surface rupture of the earthquake is only more than 10 km long, which does not match the M8 earthquake, so the seismogenic structure and mechanism of the Sanhe-Pinggu M8 earthquake still need to be further studied.