The invention provides a runoff plot ridge construction method capable of preventing runoff lateral leakage. After ground surface vegetation is removed from the ground surface on which a runoff plot ridge will be implemented, templates are erected in parallel at the position where runoff plot will be arranged, and earth filling is performed among the templates. The layered filling and compaction in layers are adopted during earth filling, till the ground rammed part is higher than the ground surface and reaches the design height; the templates are removed, and the outside surface of a ground rammed earth body is fixed by spraying adhesive for a sand sculpture, so that a protective layer of the adhesive for the sand sculpture is formed; after solidification of the protective layer gel of the adhesive for the sand sculpture, the gel exterior is plastered with mortar. The invention further provides a leakage-proof runoff plot ridge. According to the construction method provided by the invention, under the low-cost construction conditions, the runoff plot lateral leakage is prevented, and the observation data accuracy and rationality of the water-soil conservation runoff plot are improved; and the problems that the runoff lateral leakage of the through gap position at the ridge bottom occurs frequently due to the construction of a traditional runoff plot ridge, thereby resulting indeviation of the soil erosion distribution observation law of the runoff plot surface from the actual law are solved.