The laser-ranging interferometer (LRI) serves as a core payload for space-based gravitational-wave missions, as well as for gravity recovery missions. In this work, a ground-based simulator reproducing a three-spacecraft formation with six interferometric links is developed to emulate a subset of the on-orbit configuration of space-based missions. The formation is realized on air-bearing platforms forming a 10 m equilateral triangle, thereby providing a dynamic experimental environment. Each spacecraft (S/C) carries a complete set of in-house developed interferometric payloads, including an NPRO laser, a laser frequency stabilization system, two optical benches, and an integrated field programmable gate array (FPGA)-based electronics unit. The FPGA implements key functions, including weak-light phase locking, phasemeter, and differential wavefront sensing (DWS). In experiments, all six laser links are successfully established and operated simultaneously, effectively reproducing the configuration of an on-orbit S/C interferometer. At 4 mHz, the laser frequency stability is better than $80\mathrm{Hz}/\sqrt{\mathrm{Hz}}$, the weak-light phase-locking control noise is below $2\times {10}^{-4}\mathrm{rad}/\sqrt{\mathrm{Hz}}$, and the pointing stability is better than $4\mathrm{\mu }\mathrm{rad}/\sqrt{\mathrm{Hz}}$. The optical bench and the air-bearing platform exhibit displacement noise at the micrometer and sub-millimeter levels, respectively. This work provides a systematic and multi-perspective validation of S/C formation interferometry for space-based gravitational-wave detection, laying an important experimental foundation for future space missions.

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• Gravitational wave detection
• Laser applications
• Space science
• Tunable lasers
• Gravitational wave detectors
• Homodyne & heterodyne detection
• Lidar
• Optical interferometry