The open environment of grid computing raises new challenges for security. The dynamic contexts of systems could let processes run under uncertain states, and then might compromise system. At present, many theory models had been put forward for secure contexts detect. But high payload and special requirements let these models hard to be implemented. In this paper, we study security property for process in dynamic contexts which can be reconfigured at runtime in grid computing environment. We propose that context of process is secure when all subjects and objects visited from it satisfy lattice property. We also define a suitable equivalence relation among processes and puts forward security property based on lattice. We show that the novel security property is easily implemented on dedicated system.