Steroidal saponins in Rhizoma Paridis attract scientific attentions for their structural diversity and significant bioactivities. In this work, an ultra performance liquid chromatography coupled with a hybrid quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) was used to rapidly separate and identify steroidal saponins from the extract of the rhizome of Paris polyphylla var. yunnanensis (PPY). The fragment ions from glycosidic and cross-ring cleavages offered a wealth of structural information that is indicative to the aglycones, sugar types and the connecting sequence of sugar units. Based on the exact mass information, the fragmentation characteristics, and the LC retention times of 21 reference steroidal saponin standards, 98 constituents were tentatively identified with their structures proposed, which covered more than 30 types of steroidal aglycones. The 98 constituents consist of 22 pairs of structural isomers, and 40 steroidal glycosides that are identified for the first time from the nature.