The invention discloses a building groundwater sampling device. The building groundwater sampling device comprises a water drawing well, wherein a screen mesh is transversely arranged in the water drawing well; the screen mesh is embedded on the water drawing well; a sampling pump is mounted near a well mouth of the water drawing well; the sampling pump is detachably connected to the water drawing well; a connection pipe is arranged between the sampling pump and the water drawing well; the bottom of the connection pipe is arranged in the water drawing well; the top of the connection pipe penetrates through the sampling pump and is connected to a first flow guide pipe; the connection pipe is connected to the first flow guide pipe through a clamping hoop; one end of the first flow guide pipe is connected to the connection pipe; the other end of the first flow guide pipe is connected to a handle; an articulation device is arranged at a junction part of the handle and the first flow guide pipe; the bottom of the articulation device is connected to a support pipe; the support pipe is of a bent structure. The building groundwater sampling device is compact in own structure, simple to assemble and convenient to use and is capable of more conveniently drawing the underground water into the sampling pump; the flow guiding and sampling are facilitated; the working efficiency is greatly improved; the waste of manpower and material resources can be avoided; one man can operate the building groundwater sampling device.