Besides the adoption of range-gated to eliminate the backscatter, another way to advance the performance of underwater laser imaging is denoising of the images. Soft-morphological was introduced based on the analysis of the characteristic of noise in the underwater laser range-gated images. The multidirectional structures and polarized soft transformation were designed to build a OC filter. Discrete DE algorithm was used to search the best value of repletion degree aiming at the speckle index and edge energy. The experiments show that the proposed algorithm is robust because of the ability to filter the noise and protect the edge at the same time. When compared to Lee filter and nonlinear weighted averaging multidirectional generalized morphological filter, the performance of the proposed algorithm which is universal at a certain extent is better.