In order to evaluate the effect of applying gypsum on soil electric conductivity(EC), statistical analysis method was adopted, and soil EC and pH of 1︰5, 1︰1 soil/water and saturated extracts were also measured. The results indicated that without gypsum there were significant correlations between ECe and EC1︰1, ECe and EC1︰5, and the correlation coefficients were 0.988 and 0.979, respectively. After added gypsum, the ECe and EC1︰5 both increased and a fairly good linear relation was still between them, of which relation equation was: ECe = 1.42 + 6.86 × EC1︰5(r = 0.980**). Application of gypsum could significantly improve the soil alkalization and reduce the soil pH. In this experiment, 3 g/kg (0.6 kg/m2) was the best application amount of gypsum.