Abstract: In order to find out the reason of occurrence feature of No.5-2 coal seam in Shenmu mining area,the trend analysis is used to research the seam thickness and it’s bottom altitude based on 172 boreholes’ data in north-ern Shenmu mining area.The trend analysis shows that the coal thickness is generally thicker in southern and northern part than that of central part and thicker in eastern than that in western part.The bottom elevation of southern and northern area is higher than that of central area,and higher in eastern than that in werstern area.The relation between coal thickness and it’s bottom elevation is studied.The result shows that there is positive correla-tion between them with some partical area.Under the background of regional tectonic stability,the cause of their formation and it’s control to occurrence feature of coal are analyzed on the view of deposition and erosion.It is suggested that the coal occurrence feature is controlled by deposition and erosion;The deuteric deformation has only small influence.