Different polarization incidences and/or inflections yield different polarization scattering powers. The problem of searching optimal polarization state for the maximal polarization receiving power (PRP) is of significantly meaningful. Usually, there are no analytic solutions to the problem and current numerical methods are time consuming. Aiming to reduce the computational time, fast optimization mechanism is studied in this paper. An improved Lagrange method (ILM) based on bisection strategy is proposed for monostatic condition. This method takes the advantage of monotonicity of a cost function constructed by Lagrange multiplier to accelerate searching speed. The performance of this method is validated by comparing with the Lagrange method proposed by Chen (LMC). Numerical experiments demonstrate that the proposed method in this paper is superior to the existing method.