**5. Conclusions**

Based on emergy theory, this study establishes the sustainable development indexes of logistics parks, including EER, ELR, EYR, and EISD. Taking a Logistics Park as an example, this study analyzes and evaluates the data of the logistics park and proposes that the park should reduce a proportion of external purchasing emergy, improve the emergy structure, enhance the operational efficiency of the park, improve EYR, implement green logistics, and reduce the environmental load ratio and other sustainable development suggestions. The study provides decision-making suggestions for park managers.

Emergy theory can be applied to the comprehensive evaluation of sustainable development of logistics parks, which can better meet the requirements of evaluation and analysis, and has operability. By establishing the emergy evaluation index system of logistics parks, the system composition and functional structure of logistics parks can be analyzed, the relationship between logistics parks and external environment can be reflected, and the comprehensive evaluation of logistics parks from economic and ecological perspectives can be realized.

Our model evaluates the sustainability of the logistics park based on the input and output resources of the system. Social problems, threats, and risks faced by investors, and so on, are difficult to quantify, which is the next direction we are trying to explore. In the future, we will conduct further research on the correlation between various elements of the system and the economic and ecological benefits of the logistics park, so as to improve the sustainability of logistics parks. Emergy theory can be further applied to all aspects of the logistics system, which is of great significance to the sustainable development of the logistics industry.

**Author Contributions:** Conceptualization, C.W. and H.L.; methodology, C.W.; investigation, L.Y.; resources, H.W.; data curation, C.W. and H.L.; writing—original draft preparation, C.W.; writing—review and editing, C.W. and H.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research is supported by Humanities and Social Sciences Research Projects of Anhui Universities (No.SK2019A0538), Key project of natural science research in Universities of Anhui Province (No. kj2019a0673), Teaching and research project of quality engineering in Anhui Province (No.2018jyxm1035), Key scientific research projects of Suzhou University (No.2016yzd11), Key Support Program of Anhui Provincial University Excellent Talent (No.gxyqZD2019078), Research project of Suzhou University (No.2019jb12), Program for Innovative Research Team in Suzhou University(No.2018kytd01, No.2018kytd02), Key research base project of Humanities and Social Sciences in universities of Anhui Province(No.SK2018A0474) and Open research platform of Suzhou University(No.2019ykf19).

**Conflicts of Interest:** The authors declare no conflict of interest.

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