The invention relates to the technical field of a liquid sampling device in an oil well pipe, in particular to a built-in pipeline lofting device which comprises a pipe body, a valve body, a valve core and a liquid-taking tube; a pipe cavity is arranged in the pipe body, the valve body is fixedly arranged on the pipe body; a valve core mounting hole is arranged on the valve body, and the valve core is arranged in the valve body and moves by the valve core mounting hole, and a valve hole communicating with the outer part of the pipe body is arranged in the valve core and is communicated with the pipe cavity; a stream-conducting hole is arranged in the inner part of the liquid-taking tube, and the liquid-taking tube can be arranged on the valve body and drives the valve core to move for leading the stream-conducting hole to communicated with the pipe cavity with the valve hole. The lofting device has reasonable and compact structure and convenient usage, and the valve core mounting holeis opened or closed by driving the valve core by the liquid-taking tube, and the device can extract the liquid from the pipe column and adjust the flow rate of the liquid, therefore, the device has the characteristics of not affecting liquid flow in the pipe column, convenient and high-efficiency sampling, easily controlling sampling flow rate, safe and labor-saving operation and environmental protection and sanitation.