The invention discloses a measurement method of cation exchange capacity in soil. The method comprises the five steps of preparing a soil sample, carrying out exchange elution with an EDTA-ammonium acetate mixed solution and 95% alcohol, distilling by a full-automatic distiller, measuring by an instrument, and calculating. According to the method, optimization and improvement are carried out on soil sample extraction and leaching conditions, the full-automatic FOSSKjeltec8400 distiller is selected, relevant test conditions are optimized and screened, and concentration and volume conditions of absorption liquid are improved and optimized, so that the cation exchange capacity in the soil can be accurately measured. The method has the advantages of being simple and convenient as well as rapid and accurate in operation and good in repeatability.