In order to address the high nitrogen oxide emission concentration from traditional kiln flue gas SCR denitrification, poor sulfur resistance stability of the catalyst,and surface ash accumulation,the medium and low-temperature SCR denitrification device of the 200,000t glass fiber tank furnace of Jizhong New Materials as the object were taked by the project. A flow-directing grating was installed in the inlet flue to guide the flue gas to diffuse and flow. An ammonia injection grating was set up to promote uniform mixing of ammonia and flue gas, ensuring the catalyst achieves the best performance and enhancing denitrification efficiency. The catalyst was made in a honeycomb shape and arranged in three layers, significantly increasing the specific surface area. A wear-resistant layer was installed at the front end of the catalyst, increasing the transverse hardness to 0.8 MPa and the longitudinal hardness to 2.3 MPa, with the overall wall thickness reaching 0.9 mm. Additionally, the composition ratio of the custom-made catalyst was adjusted to ensure the optimal reaction temperature is between 170 and 380 ℃, improving the NOx conversion rate. After the technical renovation, the nitrogen oxide emission concentration was reduced from 140 to 30 mg/m3, achieving ultra-low emissions.