Landscape connectivity, as a dominant factor affecting species dispersal, reflects the degree to which the landscape facilitates or impedes organisms' movement among resources patches. It is also an important indicator in sustainable land use and biological conservation. Least-cost model originates from graph theory, and integrates the detailed geographical information with organisms' behavioral characteristics in the landscape. Through cost distance analysis, this model can describe the species connectivity in heterogeneous landscape intuitively and visually. Due to the simple algorithm performed in GIS packages and the demand of moderate data information, least-cost model has gained extensive attention in the evaluation of large-scale landscape connectivity. Based on the current studies of landscape connectivity, this paper elaborated the significance, principles, and operation processes of least-cost model in evaluating landscape connectivity, and discussed the existing problems of the model in its practical applications, which would benefit the further related studies and biodiversity conservation.