Abstract: To ensure the stability of the orbital configuration of the space gravitational wave detector, the design and optimization method of stable formation configuration of the large-scale spacecraft in space was studied. Considering the influence of the sun-earth-moon gravitational field on the formation configuration, the earth, the moon, and three spacecraft were regarded as a formation for research in the heliocentric coordinate system. Based on dual quaternion, the natural/artificial celestial body dynamics model was established, and the space gravitational wave detection system model with and without a central celestial body was uniformly described. The parameters to be optimized based on genetic algorithm were given, and the optimization objective function was designed. Simulation results show that the detector meets the stability requirements of the orbit configuration within one year without orbit control.