The pollution of heavy metals in the soil will affect the quality of agricultural products, which could further influence human health. Multiple heavy metals are usually detected with chemical methods in soil, during the process, strong oxidizing materials would be used to digest the samples in the laboratory, and finally, the dissolved solutions are tested. X-ray fluorescence spectrometry could realize the rapid detection of multiple heavy metals in soil, but compared with chemical methods, which has a higher detection limit. For mercury, the national pollution limit is lower than other metals, which makes it difficult to detect rapidly with X-ray fluorescence spectrometry in low-content samples. In this paper, an enrichment device was designed to realize the enrichment of mercury in soil, after testing with the X-ray spectrometer, the rapid detection of mercury in soil could be realized, which met the requirement of the actual test. The soil samples that had been weighed accurately would be heated first, and in this process, the mercury would be desorbed, and at the same time, the filter membrane was used to adsorb it, so as to realize the enrichment of mercury. A mercury generator was used to provide the air with a certain amount of mercury, and different kinds of membranes would be used to study the effects of adsorption. The result found that carbon fiber filter membranes have a good effect on adsorption and could enrich mercury in the air. When different flow velocity was adopted with the same weight of the samples, and the desorption temperature was set up at 800 ℃, the adsorption behavior of two membranes was studied. The results showed that, with the increase of the flow velocity, the intensity of the first membrane decreased, but the intensity of the second membrane increased, which meant that lower flow velocity was a benefit for the adsorption of membranes. when the different amount of mercury contained in solution was added in high-purity silicon dioxide, after enriching and testing by the designed device, the working curve could be obtained with the linear correlation coefficient to be 0.998 5. And the detection limit and quantification limit could be calculated as 7.52 and 25.06 ng respectively when multiple high-purity silicon samples were tested. It meant that if the weight of the sample was 0.3 g, the quantification limit would be 0.083 mg·kg-1 in the soil. The relative deviations were no more than 11.1% for the national standard samples except one sample that was below the quantitative limit, which indicates that this method could realize the rapid detection of mercury in the soil for agricultural land.