The invention discloses a stress analysis method for a tubular bus bar, a downlead and a fitting system, which comprises the following steps of: analyzing and simulating a four-split downlead and a tubular bus bar by adopting a beam unit (beam 188) and a rod unit (link 180), and accurately solving a fulcrum counterforce; and simulating the sliding type tubular bus fixing fitting by utilizing a solid unit (Solid187); establishing tubular busbar downlead system models with different parameters through finite element software ANSYS, and analyzing the influence of each parameter on the stress of the tubular busbar constraint node; and applying the stress of the tubular bus joint to the fitting model for static analysis. The method can accurately solve the node counter-force of the tubular busdownlead coupling system, and applies the node counter-force to the stress calculation of hardware fittings, thereby improving the arrangement mode of the tubular bus downlead coupling system and thecorresponding hardware fitting design.