Comprehensive reform of agricultural water pricing and innovation in investment and financing mechanisms are essential measures to advance water-saving renovation in large-scale irrigation districts. Focusing on the introduction of social capital

this study defines the boundary conditions for investment and financing

employs orthogonal experimental design for scenario simulation

and conducts theoretical derivation and programming calculations to develop a predictive model. The model uses financial net present value(NPV)

internal rate of return(IRR)

and payback period as dependent variables

with the proportion of social capital contribution

operating income

and operating expenditure as independent variables. The results indicate that under a 100% implementation rate of agricultural water pricing reform

with no fiscal subsidy

an optimal social capital contribution ratio of 5% ～ 15% yields an IRR of 1. 5% ～ 10. 3%. When fiscal subsidies account for 10% ～ 15% of total water price revenue

the IRR increases to 5. 4% ～ 15. 6%. This model provides a practical reference for the design and evaluation of investment and financing strategies for water-saving renovation projects in Hunan Province and similar regions.