Minxian-Zhangxian M6.6 earthquake occurred on July 22,2013 in Dingxi,Gansu province.Shortly after the earthquake,we placed eight digital flow strong motion observation recording instruments in the surrounding area which were produced by Kinemetrics Company in the USA.We set up three K2 strong motion recording instruments in Yongxing village,Yongxing primary school and Dalong village.A large number of seismic records that can be used to better understand the effects of earthquakes on the loess layer were obtained.Up to August 11,172 （516） seismic records were acquired,including 48 earthquakes of magnitude ML ≥ 3.The maximum magnitude was ML4.4,and the maximum acceleration value was 65.9 gal.From the observed data of strong aftershocks from the Yongxing array,we selected records of large magnitude aftershocks for analysis.The Minxian ML 3.8 earthquake record from August 8th was the largest,and we focused on those results.The results showed that the maximum acceleration value decayed rapidly with increasing distance from the epicenter,and the largest acceleration value was from Dalong village station,which was the nearest station from the epicenter.Because of the presence of a thin and soft loess layer in the observation area,the acceleration records from the Yongxing village station and the Yongxing primary school station could not be directly compared with those from Dalong village,but we conducted a further spectrum analysis on each record,and the effect of absorption by loess on the high-frequency components was significant.To further explore the impact of topography on the observed values,we further expanded the scope of the data filtering,and used the seismic data of four ML ≥2.5 earthquakes as the basis for measuring the peak ground acceleration value of each station.We conducted Fourier analysis on the records,obtained the dominant frequencies,and illustrated the Fourier spectrum of some typical records.The results show that the dominant frequency of Dalong village is 5.2 Hz,that of Yongxing village is 4.1 Hz and that of Yongxing primary school is 5.3 Hz.Noted that Dalong village was in foothills and its observation point was bedrock,the dominant frequency of acceleration was higher.The survey also showed that low frequency and high intensity events had greater destructive power for buildings.The seismic observation of ML3.8 earthquake indicated that the acceleration records of NS direction of bedrock point are larger than vertical direction,which is related to the focal mechanism of the earthquake.The observation results are slightly different than the previous observation in isolated peaks,because the magnitudes of earthquakes are small,and the observation distance is near,the influence of epicentral distance may exceed the influence of topographic factors,which is too complex to be further studied.