To meet the picometer-level ranging accuracy requirements for space-based gravitational wave detection, this paper proposes an optimization method for the inter-spacecraft optical metrology noise link metrics. The method optimizes the design parameter to ensure the inter-spacecraft ranging accuracy while improving the technical feasibility of the spacecraft design. Firstly, the design parameters and objective functions of the optimization problem are clearly defined, and Sobol sensitivity analysis is used to effectively identify the key parameters. Subsequently, the optimization problem is solved using the Non-dominated Sorting Genetic Algorithm II (NSGA-II), from which the optimal solution is selected from the Pareto front based on the requirements. On this basis, the design metrics for each parameter are determined, and an initial metric tree is constructed. Simulation experiments verify the feasibility of the method. The results show that by optimizing the noise link metrics in accordance with the proposed approach, it is possible to achieve an optical metrology noise level of 8 pm/$\sqrt{{\mathrm{Hz}}} $ while obtaining the most technically feasible design solution. This study provides a valuable reference framework and approach for the construction of the metric system in the subsequent spacecraft design phase, demonstrating strong applicability and laying the foundation for future gravitational wave detection missions.