The laser scattering and absorption of algal particles is the main reason for the attenuation of underwater blue-green laser communication performance in seawater. In this paper, based on the discrete dipole theory, five kinds of particle models of agglomerated core-shell cyanobacteria are established, including double ellipsoidal, four ellipsoidal, columnar filamentous, ring filamentous, and S filamentous ones. The extinction absorption and scattering coefficients of the core-shell algae particles at 532 nm of the blue-green laser are calculated as a function of the size of the core-shell cyanobacteria particles. Based on the uniform mixed layer theory, the scattering intensities of the core-shell cyanobacteria models versus scattering angle with and without an intermediate mixed layer are compared, and the influence of particle size on the scattering matrix elements is calculated for the five core-shell cyanobacteria models. The calculation results show that the absorption and scattering coefficients of the five kinds of algae at the band of a blue-green laser increase with the increase of particle size, and the forward scattering intensity is the largest. In contrast, the scattering intensities of the five models decrease with the increase of scattering angle, and the scattering matrix element ratios of several kinds of large size algae models fluctuate more. These research results lay a foundation for the study of blue-green laser scattering and absorption characteristics of underwater suspended algae particles as well as the modeling of underwater blue-green laser communication channels.