Abstract：We propose in this paper an improved optimal step-length integral iterative method. Based on the optimal integral iteration method for potential field downward continuation, we use the information in the current iterative step of the iteration method to modify the iteration scheme. The essence of this improved iterative method is divided one-step iteration into two-step iterations, and each iterative process uses the same iterative form of the integral iteration method. Therefore, the calculation amount of the improved iterative method is not increased significantly, and the convergence is the same as the optimal iteration method. The comparison analysis of theoretical model and real gravity data shows that the continuation precision of the improved iteration method is more accurate than that of the other methods, such as optimal step-length integral iteration, the Taylor series iteration and the derivative-iteration.
