The invention discloses a depth-setting thin silt sampler and a silt sampling method applying the same, which belong to the technical field of silt sampling devices and sampling methods and are intended to solve the problem in the prior art that sample grabbing can be easily affected by environmental factors and that the representativeness of collected sample is not high. The depth-setting thin silt sampler is characterized in that a detachable end enclosure is arranged at the bottom end of a sampling tube, and a sealing cover is articulated with the top end; an elastic locking part is arranged in the cavity of the sampling tube, the top surface of the sealing cover is connected to a driving part, and a connecting part is also arranged on the top of the sampling tube. The structure of thesampler disclosed by the invention is simple, the manufacturing cost is low, the sampler is convenient to use, the influence of environmental factors (such as water flow and silt viscosity) on the sample is little, and the sampler is applicable to depth-setting sampling at a place with great water flow and thin silt. The invention correspondingly discloses the silt sampling method applying the sampler, which has the advantages of simple operation steps and high collected sample representativeness.