The dry and wet seasons are obvious in karst areas of Guangxi, which can result in the occurrence of cracks because of swelling and shrinking of dryland soil, thus, may change the storage and migration of water and nutrition in soil. In this paper, the sugarcane soils located in Guanxi Academy of Agricultural Sciences in Nanning was used to study the variation of linear extension coefficient of soils and to simulate the shrinkage curves of soils under the tillage and no-tillage conditions by the software of soil shrinkage simulator software (SSS). The results showed the SSS software could fit the measured data well (R²＞0.94). Under the tillage and non-tillage conditions, the linear extension coefficient was significantly positively correlated with soil moisture content, which indicate that the higher soil moisture could result in greater linear extension coefficient and finally more obvious shrinkage of the sugarcane soil. Compared with the no-tillage condition, the tillage treatment could change the distribution of soil moisture, adjust soil structure, improve soil properties and enhance soil shrinkage. The above results could provide the reference to the sugarcane cultivation and preservation of soil water and fertility in the karst region, Guangxi.