Abstract-Cloud computing became an emerging technology.The benefits have made a lot of institutions and companies looking to use this technology. The process of migration from legacy systems to cloud computing environments is a complex process. The migration process does not represent the movement of data, applications and service only but also presents the process from the early stages of planning and continue until after the selection and transfer of data to a specific deployment model. Security is the biggest concern to consumers during the migration process, whether immigration initial from legacy systems to the environment of cloud computing or migration between the clouds. This paper presents an overview of the security requirements: before, during and after the migration from legacy systems to cloud computing, as well as security requirements data migration between the clouds.