Abstract: The remediation of black and odorous water bodies in rural areas is directly related to the improvement of the rural living environment and the advancement of ecological civilization. Reasonably determining the cost indicators and investment estimates for rural black and odorous water body remediation projects is not only an important support for promoting comprehensive rural environmental management but also an effective pathway to achieving refined project management. By comparing the investment estimates in the implementation plans with the preliminary design budgets of 10 pilot projects for rural black and odorous water body remediation in City X, the main economic indicators of remediation projects and their influencing factors were explored. The results indicated that due to the diverse types and dispersed distribution of pollution sources, as well as the complexity of remediation measures, there was a significant discrepancy between the initial investment estimates and the preliminary design budgets. The primary reasons for this discrepancy included insufficient depth in early-stage design, low accuracy in estimating project quantities, and differences in technical standards and specific implementation measures across sub-projects. To improve the accuracy of investment estimates, it was recommended to strengthen early-stage planning and design, clearly define the remediation scope, content, and major project quantities, refine the design schemes, and improve key cost economic indicators to ensure that the investment estimation accuracy should meet the required standards. The economic indicators of major sub-item projects calculated based on the preliminary design budgets can provide a decision-making basis for early-stage investment control in similar projects and serve as a practical reference for rural water environment remediation.