The hydraulic properties of hydric soils in Tibet’s peatlands significantly influence hydrological processes and play a substantial role in carbon cycle. Soil hydraulic studies on the peatlands remain strikingly limited. By the comparison of six hydraulic parameterizations using either van Genuchten-Mualem (vGM) or Kosugi saturation function, the results indicate that the PDI (Peter-Durner-Iden) model remains an excellent choice for these multi-disperse systems composed of mixed components, despite substantial discrepancies in the micrometer-scale morphology of structure and composition of partially decomposed Sphagnum and vascular tissues and mineral particles. The bi-modal scheme does not adapt well in the later stages of the Evaporation Experiment (EE), as of the bi-modal scheme deviates in the dry range of the water retention curve (WRC). Nonetheless, Irrespective of the saturation functions, the bi-modal with PDI yields satisfactory results for the WRC and the hydraulic conductivity curve (HCC). We attribute this to the complementary effects of two uni-modals. But for bi-modal PDI scheme, vGM demonstrates better performance than the Kosugi in high clay content samples. These clay-rich samples exhibit a broader and more heterogeneous feature in the equivalent Pore Size Distribution (PSD), while other samples generally show a broad and relatively homogeneous feature. Therefore, we conclude that the WRC and HCC are jointly determined by structures and compositions of mixed components of lignocellulosic, humin and mineral materials. Intricate nature of these components underscore the necessity for extensive comprehensive field sampling and laboratory analyses to accurately capture the hydraulic characteristics in the peatlands of Tibet.