which combined the characteristics of the conjugate gradient iteration
regularization and Successive Over Relaxation technique(SOR)
is proposed. The process of convergence can be speeded up and the smoothness of the solution can be enhanced by means of the conjugate gradient iteration as the pre-iteration of next SOR iteration. The solution obtained from the first step treatment is used as the initial solution for the second step. The two-segment method can achieve an accurate and stable final solution to this problem. This method is examined with the national standard particulate samples and the theoretical noisy signal. The results show good properties and is able to distinguish multi-peak particle size distribution (PSD) and robust against the noisy signal.