Parameters of rock and soil materials are the key factors in the calculation of landslide stability，but these parameters necessarily exist with some uncertainty.This reduces the reliability of stability evaluations and has an important influence on engineering safety，engineering design optimization，and other aspects of engineering.The Dempster-Shafer （D-S） evidence theory is the most efficient method of solving the uncertainty of multiple parameters.It is a kind of expansion of probability theory that is able to not only distinguish between uncertainty and what is unknown but also deal with the uncertainty caused by unknowns.The D-S theory can provide consistent results by means of combining independent pieces of evidence and dealing with synthesis problems of fuzzy and uncertain information.It has been adapted to and achieved sound results for problems in artificial intelligence，system decision-making，diagnoses，assessment，and other practical problems in various fields.In this study，the D-S evidence theory was introduced to select and estimate slip soil mechanics parameters.The parameter selection and the revised counter-calculation of the selected parameters of a typical loess-red layer interface landslide in the Gansu province were conducted on the basis of the D-S combination rule.First，combined with the huge actual mechanical parameters of slip soil of the loess landslide by tests，the D-S evidence theory was adopted to D-S evidence analysis of huge mechanical parameters of slip soil of the loess landslide.Thus，the discernment frame and basic probability assignments of the mechanical parameters of slip soil were established from the subjective and objective aspects.Secondly， the D-S combination rule was applied to combine the reliability of multiple test parameters to achieve the optimal mechanical parameters of sliding zone reliability estimates.Finally，a revised counter-calculation of the slip soil mechanics parameters was applied for the demonstration of the obtained parameters.The results show that the D-S evidence theory is an effective approach to estimate and select the slip soil mechanics parameters.The parameters obtained from the D-S evidence theory coincide with the revised counter-calculation analysis of the slip soil mechanics parameters；such results show that the theory is applicable to dealing with the uncertainty of the above parameters.Furthermore，the slip soil mechanics parameters obtained from the D-S evidence theory can help to better reflect the actual conditions of the landslide，providing a reliable basis for the stability evaluation of loess landslides.In addition，the mechanical parameter estimation of loses landslides based on D-S theory are valid and reliable；moreover，it plays an important role in geotechnical engineering laboratory test data processing and stability calculation of mechanical parameter selections and is significant in the stability evaluation of the loess landslide.