Abstract: Swelling tests on remolded Mengzi expansive soil immersed with water,salt water and acid water were carried out by use of the simple consolidometers.Swelling characteristics of the expansive soil under different initial conditions were studied.The Dose Response model was used to fit the rules of swelling time interval for expansive soil immersed with water.The quantitative relationship among the swelling and over burden pressure,initial water content and initial dry density was attained by use of the ternary regression analysis.The rules of swelling for samples immersed with salt or acid water were similar to those of samples immersed with water.The swelling ratio of samples immersed with salt water was lower because of the seepage water pressure of salt water.The higher the concentration of the acid water,the higher the swelling ratio of samples and the longer the stabilization time.The important index obtained could be provided to the engineering design,construction and stability evaluation of expansive soil slopes.