Fishing Town in Hechuan District of Chongqing,as an ancient battlefield, has important cultural, historical and military values.In order to avoid geological disasters, protect cultural relics and scenic spots ,and make sure the safety of surrounding residents and tourists, we should research the features of sandstone weathering of this site. According to the geological environment of Fishing Town, we divided rock mass of the cultural relics into 6 layers, and analyzed the water quality of surface water and groundwater of the area. Meanwhile ,we obtained rock coring samples at different depths of stratum No.6 and conducted half quantitative X-ray diffraction(XRD) test and X fluorescence chemical composition test. Since the cultural relics were mainly found in sandstone stratum No.6, we carried out identical tests of weathered samples at different positions of this layer, in association with analysis data and comprehensive comparison. Test results show that the contents of quartz and calcite in weathered samples are larger than those in rock core samples; moreover, reducing of feldspar content at different degrees and soluble salts such as gypsum play a significant role in rock flake weathering.