Abstract: Background The traditional evaluation of soil and water conservation effectiveness is faced with problems such as non-linear correlation between indicators and unreasonable weight distribution. The error rate of the combined method of DEMATEL and ANP in complex system evaluation is lower than that of the traditional model. The comprehensive evaluation of soil and water conservation benefits of production and construction projects is carried out, and the key influencing factors and their weights are identified, which provides a reference for the evaluation of soil and water conservation benefits of similar projects. Methods Taking the project of Hudong flood detention area in Shandong Province as the research object, the DEMATEL method is used to determine the influence relationship between the index factors, and the ANP method is used to determine the comprehensive weight of the evaluation index. Based on the evaluation of soil and water conservation effect of fuzzy comprehensive evaluation, a network analysis structure including 6 criterion layers and 16 index layers is established, and the evaluation index system of soil and water conservation benefit of production and construction projects is constructed. Results The loss intensity grade (c3), soil loss control ratio (c2) and soil erosion control degree (c1) have high centrality, which are 2.2620, 2.2756 and 2.4551 respectively, which directly affect the overall evaluation results. The ANP weights of the number of serious hazard events (h2), the number of disorderly disposal or downhill slag (w2) and the number of temporary measures not implemented in time and not in place (m3) are 0.1683, 0.1406, 0.1230, which should be given priority as the core basis for decision-making. Residue protection rate (w1), vegetation coverage rate (m4), forest and grass vegetation coverage rate (m5) are important indicators to connect the top and bottom factors, and have the function of connecting the preceding and the following in the system. The comprehensive evaluation indices of soil and water conservation effectiveness for the Hudong Flood Detention Area Project in Shandong Province from 2019 to 2022 were 0.749, 0.576, 0.823, and 0.712, respectively, with the effectiveness rated as good, moderate, excellent, and good, indicating an overall favorable performance. Conclusion The soil and water conservation measures implemented during the construction of the Hudong Flood Detention Area Project in Shandong Province have demonstrated commendable performance, yielding significant ecological and hydrological benefits. The DEMATEL-ANP integrated evaluation methodology proves effective in assessing such production-construction projects, as it not only elucidates the interdependent relationships among evaluation indicators but also substantially mitigates the subjective biases inherent in conventional analytic network process applications within decision-making frameworks.