Objectives The design of the control network layout plan is the basis for achieving comprehensive optimization of quality indicators such as measurement accuracy, reliability and cost, and is also the prerequisite for ensuring project quality.

Methods A control network layout design method based on grey comprehensive evaluation theory is proposed. An evaluation system consisting of ten quality indicators was established, and the data acquisition approaches for each indicator were systematically described. The proposed method integrates grey relational analysis and comprehensive evaluation to quantify the overall performance of different layout schemes. A long-distance immersed tunnel project was selected as a case study, in which internal control network layout schemes for tunnel lengths of 5.8 km, 7.2 km, and 8.6 km were simulated and analyzed.

Results The simulation results demonstrate that the proposed evaluation system can effectively characterize the comprehensive quality of different control network layout schemes. The grey comprehensive evaluation method provides clear and stable ranking results for alternative schemes under varying tunnel lengths, enabling rational comparison and optimal scheme selection even with incomplete evaluation data.

Conclusions The proposed grey comprehensive evaluation–based control network layout design method effectively overcomes the limitations of traditional analytic hierarchy process based approaches in data-scarce design stages. It offers a practical and reliable decision-support tool for control network layout design in large-scale and long-distance engineering projects, such as immersed tunnel construction, and has strong applicability and generalization potential.