The present invention discloses a farmland underground eluviation and surface runoff monitoring integration device which belongs to the fields of environment science, agrology and plant nutrition. The device of the present invention comprises of runoff pool, eluviation disk, outlet pipe, sampling bottle and runoff collecting pipe; eluviation disk is mounted horizontally on the runoff pool at aim depth of upright soil section, sampling bottle is connected with water outlet of eluviation disk through outlet pipe to collect eluviation solution; runoff collecting pipe is a four-way pipe like a Chinese word 'Shang' containing one water outlet and three lockable infall with different high; each runoff pool is communicated with at least one water outlet of runoff collecting pipe. The present invention is particularly suitable for monitoring the affects of ground water of soil solute such as nitrogen, phosphor, pesticide and so on, specially under the condition of original monitoring, can monitor soil eluviation and runoff at the same time and the same position, the nicety is improved and the sampling process is easy and rapid.