The boulder levee at Baziyu Gully in Mengshan Mountain, Shandong Province, distributed along the flow direction at the outlet of the valley symmetrically and discontinuously, with typical arc- or tongue-shaped deposition features.. During the field trip in October 2020, we measured the gravel fabric of fifty-six boulders in the Baziyu levee. We also collected three AMS14C dating samples of dead tree trunks from the crevices or the bottom of boulders. The results are as follows: (1) the gravel fabric, sedimentary structure and combined geomorphological features of the Baziyu levee collectively indicate they are debris flow deposits; (2) the absence of fanshaped deposits, muddy surface and muddy bottom, combining with the presence of gravel layer with sand lens reveal that the levee was formed by intermittent debris flow which has low frequency but high magnitude; (3) according to the AMS14C dating results and tree colonization period, the catastrophic flooding in Baziyu levee was occurred about 50 years ago, which consistent with the historical records of recent geohazards; (4) the boulder levee at Baziyu Gully was formed by a historical debris flow, which was a rapid geomorphological disaster process induced by heavy rain, and has been modified by the later flood; (5) the formation of Baziyu levee is irrelevant to any glaciation process and the levee here is not “a typical block stream”. The reported “glacial relics” in Mengshan Mountain is unreliable due to the lack of reliable evidence of combined geomorphological features, and the lack of chronological or sedimentological evidence. In conclusion, this study provides more evidence to further strengthens the certainty that the detrital deposits in the foothill of Mengshan Mountain is caused by catastrophic flooding and debris flows.