Abstract: With the batch and level sand column experiments,and with the study object of NaCl and CaCl2 mixed solution,the particle release process influenced by Ca2+ contents was examined in this paper.The critical total ionic strength（CTIS） values were brought forward under different Ca2+contents.The research results indicate that the Ca2+ not only cannot result in particle release, but also restrain the release process obviously and intensively,and the existence of the Ca2+ will result in the descending of the concentration values which induces particle release.When the Ca2+ contents were 5%,10% and 20%,the corresponding CTISs were 0.02,0.007 and 0.0005mol/L,respectively.There was not particle release when the content of Ca2+ was 100%.All the above CTISs were much lower than that of the single NaCl solution of 0.06±0.005mol/L.The CTISs become lower with the increasing Ca2+content,which validates the restraining effect of the Ca2+ on the particle release.