Abstract: The rotary vector reducer cycloidal gear profile modification faces the challenge of simultaneously meeting high load capacity and low backlash requirements. To address this, a multi-objective cycloidal gear profile optimization model is established, with the objectives of minimizing the contact force and minimizing backlash. The modification parameters (equi-distant modification and offset modification) are treated as design variables. A multi-objective raccoon optimization algorithm with non-dominated sorting-based multi-objective coati optimization algorithm(NSCOA) is combined with an improved ideal point method for multi-objective decision-making. This approach proposes an optimization method for cycloidal gear profile modification to enhance the load capacity and reduce backlash in RV reducers. The study results show that the optimal modification combination selected after optimization is as follows: the equi-distant modification is about 0.001 35 mm, the offset modification is about -0.008 67 mm. Compared to the traditional modification method without optimization, the maximum contact force after optimization is 747.39 N, which is approximately a 16.6% reduction, and the optimized backlash is 0.003 95, which is approximately a 5.3% reduction.