Based on the observation data recorded by Gansu Seismological Network（2001-2008）,using the SAM technique for S wave splitting analysis,the 319 shear-wave splitting parameters at 7 stations are obtained in southeastern area of Gansu province.It is shown that the average polarization of fast shear-wave is consistent with the regional maximum horizontal compressional stress,it is an efficient tool to depict regional stress field.The dominant polarization direction at stations which located on active fault or cross point of some active faults is consistent with the strike of main earthquake-controlling fault.However,for some stations the fast S wave polarization directions are not consistent with the fault strikes and the direction of regional maximum horizontal compresstional stress,probably owing to the influence of local complicated crustal structure.