Abstract: When the load ratio or the ambient temperature of lignite power system is low, lignite drying process in coal mills is insufficient, which restricts the operational flexibility of the lignite power system. To address the aforementioned issues, a dynamic model of the lignite power generation system with a primary air reheater was established. The reliability of the model was verified, and the dynamic changes in thermal parameters during load variation and primary frequency modulation processes of the lignite power generation system were also dynamically simulated. Results show that the integration of the primary air reheater can increase the primary air temperature by 40-63 K to meet the demand for drying output, and the primary air temperature can be controlled within a reasonable range during loading up-down, thus verifying the feasibility of integrating the primary air reheater to improve the drying output of the coal mill.