Using the Sato single isotropie scattering model and the near-field digital seismic records from Hongshan seismostation in Hebei province, the variation characteristics of S-code Qc value in Xingtai seismic region are studied. The relationship between the Qc value and frequency is ob- tained： while the length of windows are 15-30 s, Qc= （42.9±20.7）f^（0.98±0.13） ,and while the length of windows are 40 - 60 s, Qc = （ 103.1±27.9 ） f^（0.85±0.08）. Through analyzing the variation curves of Qc along with time in different frequency point, it is found that before Longyao Mt. 5.0 earthquake on April 22, 2002, in Xingtai seismic region, the high-frequency part of Qc value changed as ＂increasing→reducing→re-elevating→shocking＂ pattern, and this pattern has certain referent significance for moderate-strong earthquake prediction in Xingtai area. It is also found in the research that comparing with Aki model, the Sato model is better for the S-code computation and analysis in Xingtai seismic region.