Abstract: There are some differences in the physical and mechanical properties of the same saturated soft soil under different sampling methods. Relying on geotechnical engineering survey projects for rail transit in soft soils, three sampling methods were adopted to carry out indoor comparative test on soft soil samples. The methods were the core tube sampler, the thick-wall sampler and the open thin-wall sampler. Based on the laboratory test results, the regularity and difference between the same indicators under the three sampling methods were compared and analyzed from the perspective of physical and mechanical properties. Based on the comprehensive analysis of the test results, combined with the changes of saturated soft soil structure under different sampling methods, the internal mechanism of index difference was analyzed. The results show that the physical properties of the core tube sample and thick-wall samples are basically the same, and the shear strength index is 2.1%~20.3% higher than these of the thin-wall samples. Compared with those of the thin-wall samples, the water content and porosity ratio of the core tube sample and thick-wall samples are reduced by about 10%, density has a small increase, about 3%, and the shear strength index has improved, an increase of 6.9%~68.3%. The change of solid and liquid composition in saturated soft soils caused by sampling method is the root cause of the difference in physical and mechanical properties.