Abstract: To further improve the efficiency of biomass energy utilization, a source-load coordinated optimization scheduling strategy considering solar thermal biomass utilization (STBU) under comprehensive demand response incentives is proposed. Firstly, on the source side, an integrated energy system (IES) coupling energy supply model with STBU is constructed, and the STBU is coupled with a power-to-gas system to achieve efficient hydrogen-blended combustion utilization of the STBU device. Secondly, on the load side, both price-based and substitution-based demand responses are introduced to improve the low-carbon performance of the IES through source-load coordinated optimization. Then, a liquid storage carbon capture system and a tiered carbon tax mechanism are introduced in the IES to enhance the system's low-carbon economic benefits, establishing an objective function to maximize the system's total revenue. On this basis, a fuzzy chance-constrained programming model considering multiple uncertainties of the IES is established. Finally, actual data from a northern region is selected to verify the feasibility and effectiveness of the model, and the impact of multiple uncertainties on the operating costs of the IES is analyzed. The results show that the model has good economic and low-carbon performance. An increase in uncertainty raises the interaction costs between the system and the external power grid.