To reduce the phase error caused by the nonlinear response in the measurement system, this paper proposed a fast self-calibration method of the Gamma factor based on the Fourier transform. In this method, Fourier transform of the captured grating fringes was performed to convert the image from the gray-scale domain to the frequency domain. Then, the high-order harmonic components and fundamental components of the distorted grating fringes were found in the frequency domain. The optimal pre-encoded Gamma value within the real number range was searched by an optimization function to minimize the power ratio of the high-order harmonic components to the fundamental components and complete the Gamma value self-calibration of the measurement system, which thereby effectively reduced the phase error in the actual measurement process. On standard planes and actual measurement objects, the method in this paper was verified by experiments and compared with classic phase-error correction algorithms. Experimental results prove that this method can suppress Gamma nonlinear response to a great extent. It is simpler and more efficient than existing phase-error correction methods and improves measurement accuracy and measurement efficiency.