Abstract: Wavefront curvature sensor is used in the fields of adaptive optics and optical metrology. It is assumed that the intensity of the incident wavefront is uniform in these fields, which does not conform with the fundamental theory. The signal expression of wavefront curvature sensor under nonuniform intensity was presented by means of Fourier optics theory. The numerical analysis of signal error for Gaussian beam was conducted using the signal expression under uniform intensity and nonuniform intensity. The analysis indicates that there is an error when wavefront curvature sensor is used to detect Gaussian beam. The error reaches the maximum when the phase distribution is 4th Zernike polynomials. The error decreases as the order of Zernike polynomials increases. The error of divisional mean curvature signal is small and below 10% generally.