Abstract: In the field of industrial automation, the accuracy and reliability of level measurement technology are crucial for process control and quality assurance. Given the limitations of existing calibration methods in long-distance and high-precision measurements, this study has developed a new high-precision calibration system based on the 80-meter high-precision large-length laser interferometer at the National Institute of Metrology of China. The system provides standard values with an uncertainty of U=\mathrmQ\left0.15\mathrm\mu \mathrmm, 2\times 10^-7L\right （k=2）outside the triangular area formed by the three light beams. The calibration measurement range is 0-70 m, and the expanded uncertainty of the reflective level gauge with a graduation value of 0.1 mm is 0.3 mm. The system has wide applicability and can meet the calibration requirements of buoyancy level gauges and high-precision magnetostrictive displacement sensors through the design of specific tooling fixtures. The measurement range covers 0-80 m, with high measurement efficiency, as the measurement time for each calibration point does not exceed 15 seconds. Quantitative analysis of the impact of the inclination angle on measurement results shows that an inclination of 1° can affect measurements by up to 3 mm. This new calibration system significantly improves the calibration accuracy of level gauges and has broad prospects for industrial applications.