Abstract: The storm deposits are recognized for the first time from the Middle Triassic Beiya Formation in the Beiya region, western Yunnan, and consist of alternating gravelly limestones and reticulated limestones with abundant sedimentary structures of storm deposits such as erosional soles, lag deposits, graded beddings and hummocky cross-beddings. The background deposits of the storm deposits are dominated by thin-bedded reticulated limestones with wavy beddings and bird's-eye structures, suggesting a tidal-flat environment in the study area. The discovery of the tidal-flat storm deposits may be important to the research of the palaeogeography and palaeoclimatology in the study area during the Middle Triassic.