Soil detachment, the initial stage of soil erosion, is considerably affected by the growth of plant roots and biological crusts, resulting in potential seasonal variations in soil detachment. In the red soil hilly region in southern China,,biological crusts develop extensively beneath the forest canopies due to the richness of hydrothermal resources, therefore inevitably impacting the process of soil erosion in this area. The study selected the moss crusts within the camphor forest and oil tea plantation in the red soil hilly region as the research subjects, investigating the seasonal variations in the soil detachment capacity of moss crusts and their main influencing factors. The results showed that: (1) the surface characteristics of the moss crusts varied significantly with the seasons. When hydrothermal conditions were favorable, the surface characteristics of the moss crusts were well developed, and the moss crusts began to deteriorate when rainfall decreased and drought set in. (2) As the coverage, thickness, and plant height of the moss crusts, as well as soil cohesion, were increased, soil erosion resistance rose, whereas soil detachment capacity diminished. Both rill erodibility and soil detachment capacity were declined by the development of the moss crusts. During the drought, there was a hysteresis effect in the soil detachment capacity after the degradation of moss crusts, with the soil detachment capacity first rapidly increasing and then gradually increasing. (3) The seasonal variations in soil detachment capacity could be estimated with power functions of flow shear stress, soil cohesion, and biological crust coverage. It effectively elucidated the seasonal changes in soil detachment capacity caused by moss crusts development under economic forests in the region. The model accuracy (NSE=0.728) indicated that it was effective in predicting and explaining changes in soil detachment capacity. This study's investigation into the seasonal dynamics of moss crusts and the associated variations in soil detachment capacity may provide an important scientific basis for the prevention and control of soil erosion in the red soil hilly region of southern China.