Abstract: In order to analyze influencing factors of combustion performance flame spreadas height, total heat release, and rate of increase of combustion heat index during burning process of Class B1 data cables, using low-smoke halogen-free sheath materials with superior consistency in burning results as research object, class B₁ combustion tests were conducted on shielded 6A class digital communication symmetrical cables, focusing on impact of cable structure, comparison of sheath material types, and different quantities of bundled samples. Results showed that among these factors, flame-retardant performance of sheath material significantly affected burning performance of Class B₁ data cables, which could provide reference for design of Class B₁ data cables..