Cantilever mining header is a widely used roadway mining equipment in mines, which can improve the efficiency of roadway mining. The slewing platform of the header is an important part connecting the cutting part and the machine body, which is often subject to the impact load of the cutting part and prone to failure. In order to improve the reliability of the header, EBZ55 cantilever header was taken as an example to study the structural strength of the slewing platform under different working conditions, to establish the finite element analysis model of EBZ55 cantilever header slewing platform, and to determine the two kinds of extreme working conditions according to the actual conditions. The stress distribution of the rotary table was calculated, and the maximum stress of the rotary table was less than the yield strength of the material, but there were obvious areas of stress concentration. According to the stress analysis results and the actual use of the header, the improvement of the rotary table structure was proposed.