Two linear seismic arrays are deployed across the surface rupture of 1920 M 8.6 earthquake along Haiyuan fault zone near Xianzhou, Haiyuan County, Ningxia, to receive fault zone trapped waves generated by near-surface explosions within the fault zone between the two lines. Each array consists of 14 three-component portable digital seismic stations, with the interval between two stations being 30～40 m near the fault zone and 230～250 m away from the fault zone. After filtering in a frequency range of 0.1～4.0 Hz, vertical component seismograms on Line 1 show fault zone trapped waves with relatively large amplitude, low-frequency and long-duration wave train after the S waves. Since the trapped waves arise from coherent multiple reflection along boundaries between the lowvelocity fault zone and the high-velocity surrounding rock, their amplitudes and frequencies are strongly dependent on the fault geometry and physical properties. Thus, fault zone trapped waves can be used to explore inner structures of the fault zone. The study of the fault zone trapped waves reveals that the shattereing width of Haiyuan fault zone near Xianzhou is about 250 m.