The 4-pipe-barzed specimen is used to obtain the strength of the brazed joint of the rocket nozzle skirt wall, which is made by the pipe works joined by brazing. The influence of the fillet shape to the strength of the 4-pipe-brazed specimen is numerically estimated by the finite element method with the non-linear static elastic-plastic analysis. The fillet shape is represented by the apparent fillet width and the clearance between the pipes. As far as the variation of the shape assumed in this research, the von Misee' equivalent stress in the fillet reaches to its tensile strength by the smaller nominal strain than the pipe, and rupture might always occur at the fillet. For the constant apparent fillet width of 1.0 and 2.0mm, the maximum nominal strain to rupture has the smaller extreme at clearance of 200μm.