On the basis of detection analysis method of chloride ion in soil, a detection method by calculating the theoretical conductivity and actual conductivity measurement which called precipitation conductance method was put forward. The recovery of this method was 93.40%~97.40%, and the relative sdandand deviation(RSD) was 1.91%, it was proved to be validated to meet the general requirements analysis. The operation of this method is simple. It need fewer drugs and is suitable for multitudinous sample testing.