Objective MethodIn this paper, the analysis method of cation exchange capacity in soil was optimized. In view of the deficiency of the forestry standard method of soil cation exchange quantity, a rapid method for the determination of cation exchange capacity in soil with automatic eluent and kieldahl apparatus was introduced. The analytical steps of centrifugal and distillation titration were optimized and improved.ResultOn the premise of constant principle, the parameters of the instrument were optimized through experiments. The results were as follows: ammonium acetate was stirred for 15 min, ethanol was washed for 4 times, and distilled for 5 min. Under these conditions, the precision and accuracy of this analysis method are in accordance with the requirements by testing the national soil certified reference materials.ConclusionCompared with the national standard method, the proposed method is simple, efficient, accurate and reproducible. It is suitable for the determination of the cation exchange capacity in large quantities of soils.