In mobile ad hoc networks (MANETs), the research on key management of identity-based scheme is attracting more and more attention. In this paper, we study on four types of identity-based schemes which resist key escrow problem at different degrees, and introduce several schemes for each type. Then, we give an overview of the characteristics of their key management, and made a summary of key generation and distribution. Subsequently, to build a more secure identity-based scheme for MANET, we recommend some techniques to improve security and availability of its key management. Finally, we point out some problems of identity-based schemes in MANETs, which are not addressed and we will explore in the future.