To investigate the cracking sensitivity of cement paste under the restriction of steel bars, the tensile strength of the cement paste with different mineral admixtures was tested. With steel bar embedded in each specimen to restrain the shrinkage of the cement paste, continuous strain values of steel bars were taken down, which were converted into the stress values of steel bars. Based on the assumption that the stress value of the steel bars equals to that of the cement paste wrapping around the steel bars within a certain stress, the shrinkage stress of the cement paste and its tensile strength were compared; the factors affecting the cracking sensitivity of cement paste were analyzed. The results show that, the paste cracking sensitivity will decrease with water to binder ratio mW/mB increasing in some range; when the mW/mB is same, the addition of fly ash also decrease the cracking sensitivity significantly.