Abstract: In recent years, the multi-dimensional coupling of source-grid-load-storage-market has caused a "combinatorial explosion" of calculation scenarios for annual power-grid operating-modes. Existing operation-mode calculation procedures rely on manual breakpoint-based connection, which tends to result in insufficient boundary coverage and repeated iterations. To address these issues, a generation method of calculation strategy for annual power grid operating-mode with full-scenario boundary coverage is proposed. Firstly, an overall framework is established to automate the entire strategy-generation process. Secondly, a candidate-scenario generation method coordinating probability and risk is developed to select boundary combinations worthy of calculation. Thirdly, an operating-mode calculation strategy based on grouping of in-service thermal-power capacity is proposed to search for combined unit start-up modes approaching branch thermal-stability limits. Finally, case studies on the modified IEEE 39-bus system demonstrate that the proposed method can automatically determine calculation targets from massive scenarios and identify operating modes with the highest limit-violation risk, providing a technical support for the transformation of annual power-grid operating-mode calculation from manual-experience-driven mode to automatic mode.