As the demand for large loads such as oversized cameras, antennas, and robotic arms continues to increase, the assembly tasks of medium-sized and large satellites have shown explosive growth. Compared to small satellites, their assembly is more difficult, their development cycle is longer, and they occupy more resources, placing higher requirements on the accessibility, accuracy, efficiency, and other aspects of measurement projects. This paper studies the benchmark establishment method suitable for multi-platform satellite structure assembly, analyzes the impact of the issue of “evaluating large size products with small size benchmarks” on satellite structure assembly measurement data in principle, and studies the “one point plus two vectors” coordinate construction method using the horizontal adjustment function of the instrument itself and the assembly platform transfer device in combination with the assembly process status of the rotary table and the satellite assembly bracket, The principle and implementation process of the method were analyzed and elaborated, and field tests were conducted to verify it. Through theoretical analysis and comparison of data results, the proposed benchmark establishment method was evaluated and optimized.