The different geological structures are established in terms of topography, lithology and geological structure; the catchment area is studied based on the variation of the spatial distribution of tunnel; and the kinds of main catchment topographies, geological structures and tunnel crossing modes are summarized. The varying modes of catchment area, including burialsyncline type, burialanticline type, burialmonoclinic type and nuditysingle inclined type, are introduced; and then the determination methods for catchment area in different modes are obtained. A case study is made on Jiantuowan Tunnel on ChongqingLichuan Railway. The catchment area of water inrush volume forecast of Jiantuowan Tunnel is regarded as burialanticline type. As a result, the determination of the catchment area of Jiantuowan Tunnel should be paid more attentions to.