Recently, linear generators have been widely employed to convert oceanic wave energy into electricity. Among various linear generators, linear permanent magnet generators (LPMGs) have gained attention due to their special characteristics such as high power density and simple control structure. In this paper, flat double-sided LPMG is investigated and designed.Considering all effective design variables, a particle swarm optimization algorithm-based optimization method is employed to maximize efficiency and minimize weight. The optimization results show an increase in efficiency and a reduction in the weight of the generator. Finally, the design results are evaluated and validated using magnetic equivalent circuit and finite element analysis methods.