The NC spin-forming machine center possesses excellent manufacturing properties such as high mechanical efficiency and low manpower need. It can quickly form the final shapes of parts and doesn't need more work to cut the material for the formed parts by adjusting the parameters of shaped trajectory, spinning speed and feeding rate, etc. Different processing parameters are usually needed for different materials and shapes. If the parameters set improperly, spinning failure would be incurred including break-splitting and wrinkling. In order to avoid spinning failure and obtain good quality, this paper investigates the influence of manufacturing parameters on spinning by using the Taguchi method. The purpose is to find out the optimal manufacturing parameters so as to shorten the time needed for trial and to find out the optimal manufacturing parameters. Moreover, spin-forming reliability of stainless plate on different thicknesses and lengths was also studied to evaluate the successful probability of products on spin-forming. The storage tank of a plastic shot machine is chosen as the researched object. The manufacturing parameters were set according to the results obtained in the Taguchi analysis. The allowed spun lengths of the storage tank in different thicknesses were collected to evaluate spinning reliability in cooperation with K-S identification. The purpose is to find out the relationship between the allowed spinning deformation and the thicknesses of stainless plate. The studied results can be used as a basis in manufacturing parameter adjustment and risk assessment of spin-forming.