Moving forward in digital transformation programs in many governments around the world created the need for integrating large organizations together. Large software projects have become increasingly complex. They are often formed by integrating independent software systems. As a result, system integration has gained the attention of the information and communications technology (ICT) community in complex organizations. The purpose of this research is to analyze the challenges facing the existing system integration research, especially in Large-scale Software Projects, during the last ten years. We begin by discussing large-scale software projects challenges continued by review on system integration issues and challenges facing existing approaches. Systems interoperability and the complexity of system architecture are on the top of the integration challenges. We found that most studies describe individuals and teams who have worked in isolation to develop solutions to certain problems without widespread adoption of a form of integration. Thus, more integration issues were created. Lastly, we mentioned from the current available research, the success and failure factors influencing system integration.