Abstract: The cavalcades of tectonics and sedimentation in Longmenshan area are discussed. There exist nappes of different times and in opposite directions, i.e: during late Triassic-early Jurassic, the area used to undergo a westward napping; while from the late period of late Tertiary until recent time, an eastward napping are predominant. Here we call this eastward type of nappes Longmenshan type. Areas favourable for petroleum exploration can be found under the eastward nappes, and still more promising areas are those beneath early formed nappes.