In this paper, a discrete element numerical simulation was carried out to study the influence of doped fiber on the freeze-thaw characteristics of soil. Firstly, a process controlling thawing and consolidation system was developed. Based on the thaw-subsidence test, a microscopic parameter-reduction method was proposed to simulate the thaw process. Besides, the effects of fiber content, fiber length, and soil sample height on the thaw subsidence characteristics of fiber reinforced soil were analyzed. The results show that the proposed simulation method can preliminarily analyze the thaw subsidence process. The optimal fiber content can also be obtained by the discrete element method, and the optimal fiber content is 0.1% for the simulation cases. In term of the modulus of thawing compression, fiber length and fiber content are the most sensitive two factors. However, the sample height is not as sensitive as them. The improvement of fiber incorporation on soil strength and thaw subsidence characteristics is consistent.