Abstract: The inaccurate problem of lime-content testing in lime soil subgrade is examined in combination of the actual environmental status of subgrade soil. By examining the compaction degree and water content of the mixed ash and the maintenance methods, the irrationality of sample preparation methods in the current lime-content testing are analyzed, and the preparation methods of EDTA consume testing is modified and a set methods of EDTA consumption sample preparation considering the work environment of subgrade is proposed. The comparison tests of different lime-content in two preparation methods are conducted. The results show that the attenuation ratio of the verification methods of EDTA consumption is less than that of the specification methods. The former can accurately test the lime-content of soil. The modified sample preparation is more reasonable. It offers a preparation methods of lime-content testing in subgrade which is suitable to the practical engineering.