Abstract: Measurement methods of shape factor of Y-shaped fiber were presented in this paper. Focusing on the problem of fast and accurately measuring the shape factor of Y-shaped fiber which cross-section image border is not closed, the three-point method for measuring shape factor of Y-shaped fiber was proposed to improve the existing measurement methods. The method presented in this paper was more accurate and efficient for measuring the characteristic parameters of profiled fiber cross-section, and expanded the scope of measurement parameters. A comprehensive basis of reference and evaluation for manufacture of Y-shaped fiber was provided. The measurement results indicated that the method described by this paper has good practical application.