To improve the sinusoidal feature of binarized sinusoidal fringe pattern, a new error-diffusion method based on Floyd-Steinberg error-diffusion dithering algorithm in traditional halftoning is proposed. Firstly, the error-diffusion kernel is expanded to reduce quantization error of the binarized sinusoidal fringe pattern and restrain the unsymmetrical texture. And then the error-diffusion coefficients are distributed linearly to smooth the fringe pattern and enhance the dispersion. The simulations and experiments indicate that, the proposed method smoothes the fringe pattern and reduces the phase error of 3D measurement compared with traditional Floyd-Steinberg dithering algorithm.