Megaprojects are a large-scale project with an expensive cost and long time schedule, this unique kind of projects are usually given their infamous reputation as it is often result in undesired outcomes same as enormous cost overruns and time extensions. In a lot of cases of undesired outcomes, we can predict that it is due to not managing megaprojects characteristics as skillfully as required and wrong combination of that characteristics which lead to a disaster. Improper managing the different managerial aspects of mega projects is reflecting a failure in the achievement of the project requirements especially in case of risk managements where we can say that, Mega projects is resulting a Mega risk. Risk management is currently considered to be a mandatory part of project management in general and an integral part of successful project management while the main aspect which is projects management is different from megaprojects than in other types of projects (small- and medium-scale projects) as in case of megaproject the management is more complex and complicated due to the size and complexity of that kind of projects. In this research the author studied the Risk Management in the Mega construction projects in the kingdom of Saudi Arabia (KSA) and the main objective of this research was to apply the best ways of managing the risk in case of mega construction projects starting from identifying the most significant risks which impact this kind of project in KSA and then analyze the identified risk qualitatively to determine its impact in the project objective and to find out the most significant 15 risks after the ranking of the identified risk depending on the risk importance index of every risk the research resulted in identifying 57 risks and categorize those risks in 2 main groups and 8 subgroups one of them is related the mega construction projects characteristics and then the most important risks has been determined.