Abstract: The “horizontal-arc-inclined” cut layout in the caving fully mechanized top coal face of steeply dipping and extra thick coal seam has achieved good effect. Basing on the existing condition of NO.1125 steeply dipping, unstable and incompact coal seam face in Changshanzi colliery. Comprehensive analyzing the characteristic of arc segment parameter, the adaptability of supports and conveyors, as well as the phenomenon that supports have inclined in the upper-arc. The measure that the cut layout before is transformed into the line layout have been implemented to eliminate the supports inclined accident and suitable layout relatively is line layout in the caving fully mechanized top coal face of steeply dipping and unstable incompact coal seam in Changshanzi colliery.