Construction activities taken place in ecologically fragile regions (EFRs) of China are facing a series of environmental obstacles. Studying critical success factors (CSFs) to arrive at the sustainable objectives for construction project in EFRs is needed. Understanding the interrelationships of these CSFs is one of the vital ways to achieve this. This paper identifies and analyzes 18 CSFs for construction projects in EFRs through a literature review from a multi-perspective and a case study of Korla City in China. The causal relationship between each CSF is obtained by pairwise comparisons and thereafter, an ISM (Interpretative Structural Modeling) method is employed to study the hierarchical structuring of the CSFs. As a result, we established a five-level ISM. Subsequently, an MICMAC (cross-impact matrix multiplication applied to classification) approach is implemented to partition and classify each CSF into four quadrants (independent, linkage, autonomous, and dependent) according to their driver and dependence powers. Through the implementation of an MICMAC approach, the degrees of relationship between each CSF is gained. The findings reveal that the studied 18 CSFs have a strong hierarchy and interrelationship. The project manager’s leadership style and economic viability are the root source of project success and has the highest influence, which is supported by the result of MICMAC analysis. CSF planning and implementation of sustainable strategies are more dependent and are influenced by others. The CSFs on the top level of ISM: conflict resolution, planning and implementation of sustainable strategies and resources of water play a significant role in arriving at the project success, and has a great potential for future study. The approaches implemented in this paper can be helpful for decision-makers and managers of construction projects in comprehending the interrelationships and the degrees of CSFs for construction projects in EFRs and for efficiently achieving the project success.