Abstract: When studying the mechanical properties of the roots, the roots are generally in the isolated state. At present, there is no reports on the survival time and survival status of 4 species of Caragana korshinskii Kom, Salix psammophila Schneid, Hippophae rhamnoides Linn, Artemisia sphaerocephala Krasch in vitro. Therefore, it is urgent to determine the suitable storage time and the preservation method for the study of the mechanical properties of plant roots. In this research, TTC- dehydrogenase reduction method was used to determine the root activity of 4 kinds of plant roots in the 1~4 mm diameter range in the low temperature incubator of 4℃ for 0 days, 6 days, 13 days and 20 days. The results showed that: low temperature incubator of 4℃ was more suitable for the preservation of plant root activity for a long time, the root activity of 4 kinds of plants was the rapid growth rate of decrease with increasing storage time, when stored for 6 days, the root activity of 4 plants decreased at a rate of 10%~20%, when stored for 20 days, the root activity of 4 species decreased at a rate of 70%~90%; When the storage time was the same, the root activity decreased with the increase of root diameter in the range of 1~4 mm root diameter, and the root activity of fine roots was more likely to be lost in the 4 plants.