The subject of the study was the method of assessing and analyzing the level of maturity of sustainable project management of Russian enterprises. With the help of the review of scientific literature the tendency to integration of project management and the concept of sustainable development is proved. The analysis of approaches to assessing sustainability indicators showed a lack of consistency, as well as the shift in emphasis to individual indicators and insufficient attention to institutional sustainability indicators. The problem is in the lack of a methodology for quantifying the level of maturity of sustainable project management which could become the basis for monitoring this management. The availability of monitoring is a prerequisite for a successful transition to the digital economy and data-based management as the results of monitoring can become a platform for optimizing sustainable project management by tracking sustainability indicators. As a result of the methods of analysis of literature and international professional standards, as well as in-depth interviews with top managers of enterprises, the authors substantiated the method of assessing the level of maturity of sustainable project management, the innovation of which is the inclusion of the module of institutional indicators of sustainability and integrated quantitative assessment of economic, social and environmental indicators of sustainable project management. The results of approbation of a technique by method of questioning at 19 Omsk enterprises are analysed. A group of enterprises with high and above average maturity levels of sustainable project management was identified. The indicators of the institutional evaluation module demonstrating good potential for further development of sustainable project management are fixed. The influence of the transition to the digital economy on the formation of the need to monitor the sustainability of project management is analyzed. The results can be used to optimize the processes of sustainable project management and to further improvement the methodology of evaluation of this management in the context of the transition to digitalization of the economy and management.