This work demonstrates a new approach for geometric parameters estimation of cone-beam computed tomography system from the coordinates of the centroids of 2 projected point sources sampled over 360 degrees. Nonlinear object expression was derived for the coordinates of the centroids in terms of the geometric parameters after a slice of reasonable simplification, which aims to improve the convergence and robustness of the nonlinear object expression. All of the geometric parameters could be precisely estimated from the nonlinear object expression using the annealing algorithm. The simulations and experiments indicate more excellent convergence, robustness, and precision of our approach compared with other methods. Furthermore, our approach is insensitive to the initial value; namely, we do not need to set the value close to the true value to guarantee the convergence of the approach.