The tunneling from No. 7 vertical shaft of Humaling tunnel on LanzhouChongqing railway crosses Tertiary watercontaining poorlycemented finesilty sandstone, which has extremely complex waterstable property. The tunnel face has poor selfsupport stability, and the tunneling progress is very slow. Furthermore, the effect of dewatering carried out inside the tunnel cannot be guaranteed. The tunneling has great risks. Experimental study is made on the dewatering made from the ground surface based on the terrain and geological conditions of the tunnel. The study results are analyzed, the hydrogeological property of the Tertiary watercontaining sandstone is obtained and the design parameters of the ground surface dewatering wells are determined.