Until recently, application developers could often assume a target environment that was homogeneous, reliable, secure, and centrally managed. However, with the advent of collaborative computing and data sharing, more and more new modes of interaction have evolved resulting in the need and use of distributed resources. Work within this community has led to the development of Grid technologies [II, which address precisely these problems. In grid computing, heterogeneous resources distributed geographically are virtualized as a unified whole. Grid computing, as a result, provides enormous opportunities in terms of resource sharing, maximization of resource utilization and virtualization of resources. Because of its immense potential, not only the scientific community, but also the IT enterprise communities are excited about its prospect. A recent survey ranked grid computing as sixth on priority lists for IT spending among indu stry professionals (51 . With thi s much interest, security becomes necessary to provide authentication, authorization, resource protection, secure communication, data confidentiality, data integrity, trust policies management, user key and credential management, service protection, and network security. This paper provides an insight classification of the different mechanisms and methods of security in grid computing environment, and also discusses the solutions for each category and its limitation in order to define the real problems in grid computing security. In our approach, we categorize the security solutions into Resources Level