Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm3 under three different temperatures were determined by the diffusion-cell method using 36Cl-labelled CaCl2 solution. The results showed that activation energy decreased with water content, which indicated that the threshold for diffusion was lower at a higher soil moisture rate. Therefore, the diffusion coefficient (D) of chloride ions in soil increased consistently with soil moisture. Although a near linear increase in the diffusion coefficient with increasing soil moisture or bulk density in all the soils was observed, the increase rate in different soils was not the same. The D value increased with temperature, and with temperature increased by 10℃ in the range from 5 “C to 45℃ theD valve increased by 10%～30%, averaging about 20%. Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm3 under three different temperatures were determined by the diffusion-cell method using 36Cl-labeled CaCl2 solution. The results showed that activation energy decreased with water content, which indicates that the threshold for diffusion was lower at a higher soil moisture rate. Thus, the diffusion coefficient (D) of chloride ions in soil increased consistently with soil moisture. with increasing soil moisture or bulk density in all the soils was observed, the increase rate in different soils was not the same. The D value increased with temperature, and with temperature increased by 10 ° C in the range from 5 ”C to 45 ° C theD valve increased by 10% ~ 30%, averaging about 20%.