Abstract: There always exist two different opinions about the sedimentary environments of Upper Triassic in west Qinling Mts.One is that they belong to seashore to shallow sea factes, the other is that they are attributed to bathyal slipe facies.In this article we analyse the sedimentary environments of Upper Triassic of west Qinling Mts.taking the Chebaguo section of Zhuoni County in Gansu province as an example and using the analysis method of turbidite factes, factes association and association sequences.Some important conclusions have been drawn as follows: (1) The studied section can be classified into B, C, D, E and G turbidite facies in terms of textures, structures, Bouma sequences, sand/mud ratios, and thichness of turbidites.(2) In the light of the vertical association types of turbidite factes Upper triassic can be divided into five factes associations named channel, overbank, lobe-channel transition, lobe and basin plain.(3) The studied section can be categorized into two association sequences called basin plain→lobe and basin plain→lobe→lobe-channel transition→ channel, according to the vertically stacked regulations of factes associations.(4) On the basis of analysis above, considering the regional geological backgrounds the sedimentary envioments of Upper Triassic of West Qingling Mis.are considered as sea-floor fans, characteristic of that (a) slopes along which turbidity currents were transported were relatively steep and scouring were intense there; (b) reliefs where fans were accumulated were flate, which means that basin floor fans wereformed and (c) fan bodies were relatively small and lobes were connected withchannels’Based on the above information a sedimentary model satiable for the regiones suggested’