By　using　AC　impedance　spectroscopy　(ACIS),　this　paper　studied　the　changes　of　electrochemical　parameters　of　cement　paste　mixed　with　fly　ash　(FA),　ground　blast　furnace　slag　(GBFS)　and　silica　fume　(SF)　during　the　process　of　bending.　The　results　showed　that:　the　AC　impedance　parameter　R　(s)　decreased　with　the　increase　of　stress　imposed　on　the　specimens.　Under　the　same　condition　of　W/B　and　stress,　for　R　(s)　there　were　group　D　with　SF　＞　group　C　with　GBFS　＞　group　A　of　cement　paste　＞　group　B　with　FA,　which　indicated　that　the　porosity　or　cracks　within　the　samples　were　group　B　＞　A　＞　C　＞　D,　and　with　the　increase　of　stress,　the　change　rate　of　R　(s)　of　group　D,　C　and　A　was　less　than　group　B.　At　the　same　time,　ultrasonic　method　was　used　to　test　the　changes　of　sonic　time　and　first　wave　amplitude　during　the　bending　process,　and　the　results　are　agree　with　the　changes　of　ACIS　parameters.