In this paper, an finite element numerical simulation software, ANSYS / LS-DYNA, is used to analyze the stepped spinning forming of SAE 4130 Chrome Molybdenum Alloy Steel, and the distribution rules of spinning force, forming stress and strain under single pass of forward flow forming, Then use the orthogonal array from Taguchi method, including 4 main control factors which are the PART1 roller chamfering, roller space, feed rate, and rotation speed of mold, each of them separately have 3 levels, undertaking 9 sets of analytical simulation experiments, also take the experimental goal to be minimum spinning force, so use the Taguchi quality design method of nominal the best within the orthogonal array. In this case study, the result form the calculate S/N ratios, linear graphs and response graphs of control factors display two of the biggest factors that affects neck-in spinning , they are feed rate and roller space.