Abstract: Under the curing condition at 5 ℃, filling body testing-block has been made, then the single axial compression strength(UCS) testing was carried out, based on the results, electronic scanning mirror(SEM)has be done. Comparing with the testingblock which made under curing condition at 20 ℃, this paper analyzes the microcosmic characteristics and the macroscopic strength law of the hydration reaction of the filling body. It is shown that the UCS of testing-block is obviously affected by the temperature, in the range of sand/cement ratio(S/C) is 4~10, silicate crystal of the hydrated product inside the low temperature filling body block is smaller, and the pore structure distribution of which is much more sparse and uneven, the porosity is larger than standard curing situation, the macro strength reduction is 8%~28%.