Abstract: To clarify the influence mechanism of Vicat softening temperature (VST) of low-smoke halogen-free flame-retardant materials on extrusion process, extrusion quality anomalies of LSZH-1 material processed on the HT-12 production line in actual production were taken as the research object. Comparative tests were designed to identify the root causes from the aspects of material, process and equipment. Targeted optimization strategies were proposed and verified in production. Results showed that VST of LSZH-1 material was only 84.4 °C due to its formulation system. Combined with the excessively high temperature in the feeding section and the weak pressure-building capacity of the low-pressure screw of the HT-12 line, this induced plastic bridging in the barrel, resulting in reduced outer diameter of the product and large fluctuations in barrel pressure and main motor current. By replacing with a high-pressure flame-retardant screw and optimizing the drying and feeding section temperatures, extrusion pressure fluctuation was controlled within ±0.3 MPa, current fluctuation within ±1.5 A, and outer diameter deviation within ±0.3 mm, achieving continuous and stable production. Research reveals the correlation between VST and extrusion stability of low-smoke halogen-free flame-retardant materials that the lower the VST, the easier premature softening and bridging occur, requiring temperature adjustment and stable barrel pressure, while materials with higher VST exhibit better process adaptability and stronger extrusion stability.