The invention discloses a method for building a uniform-thickness quadric surface optical hood finite element model in ANSYS. The method comprises the following steps that 1, a quadric curve equation is determined and converted into a function form; 2, an independent variable is selected according to the open direction of the model to be built, and the range of the independent variable is determined; 3, key points of density distribution are built based on an APDL compiling loop command; 4, BSPLINE commands are used for forming preliminary splines based on APDL; 5, line segment fusion is carried out on the preliminary splines in the step 4; 6, the fused line segments in the step 5 are connected to form a plane; 7, mesh generation is carried out on the plane formed in the step 6; 8, the finite element model formed in the step 7 is rotated. According to the method, the problem that a quadric surface model is hard to directly build in the ANSYS is solved, and compared with the process of directly adopting user interfaces for analysis, the defects that problems of the same kind are loaded many times, trouble is caused, manpower is consumed, and errors easily happen are overcome.