The spinning process of noncircular fiber was investigated in this work. A combination of numerical simulations and experiments made it possible to find out the optimum processing condition for shaped fiber. First, an inverse method which combined two-dimensional/three-dimensional simulation with experiments was utilized to find out the temperature and draw ratio dependent surface tension in melt spinning of shaped fiber. The surface tension as a function of temperature and draw ratio was found to be decisive to the change of cross-section. Second, an orthogonal numerical experiment and statistics analysis were carried out to determine the optimum spinning condition for the desired noncircular fiber. The optimum spinning condition was well validated by experiments. It was then proved that the integrated method in this work, including the numerical method, the inverse method to determining the surface tension, and the orthogonal analysis, can be a good solution for the design and processing of profiled fibers. POLYM. ENG. SCI., 50:1935–1944, 2010. © 2010 Society of Plastics Engineers