Rapid　urbanization　has　caused　numerous　construction　solid　waste　landfills.　Few　studies　have　explored　the　impact　of　multi-source　waste　soils　with　remarkable　spatial　variability　on　the　reliability　of　landfills.　This　study　aims　to　characterize　the　site-specific　spatial　variability　of　stockpiled　waste　soils　and　perform　a　probabilistic　stability　assessment　of　a　real-world　landfill　slope.　An　integrated　probabilistic　landfill　analysis　framework　is　developed,　consisting　of　spatial　variability　characterization,　random　field　modeling,　and　probabilistic　slope　stability　analysis.　Seventy-four　groups　of　clayey　waste　soil　parameters　were　obtained　from　a　landfill　in　Hangzhou,　China.　The　artificial　mixing　behavior　makes　the　shear　strengths　of　waste　soils　have　high　variability　(coefficients　of　variation　close　to　0.5),　a　high　positive　cross-correlation　(about　0.9),　and　bimodal　marginal　probability　distributions.　The　spatial　variabilities　of　the　cohesion　and　friction　angle　of　clayey　waste　soils　are　similar,　with　vertical　and　horizontal　scales　of　fluctuation　being　3.23 m　and　34.32 m,　respectively.　The　conditional　random　field　modeling　of　clayey　waste　soils　provides　a　more　realistic　slope　stability　assessment　of　the　landfill　and　its　impact　on　the　failure　probability　highly　relies　on　the　strength　and　location　of　boreholes.　More　slope　reinforcement　measures　should　be　adopted　for　safety　management　of　the　next　stage　of　landfilling.　©　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature　2024.