Abstract: The two key features of a grid are its dynamics and openness. The user subjects and resource objects of a grid system are decoupled, and change dynamically in time and space. Their behavior and state are composed of a series of life cycles. A user subject’s life cycles may consist of registration, logon, usage, suspending, maintenance, logout, and exit. A resource object’s life cycles may include creation, integration, deployment, usage, offline, maintenance, and exit. For grid subject or object, what is different from that of a traditional system is that its full life cycles must be considered in the process of design, usage, and evaluation of grid, which is called the full life cycle principle for grid. In this paper life cycle, full life cycle, and their productivity are proposed and defined. The relationship between these concepts is also studied. By studying the productivity of a typical grid scenario according to the principle, the usage and evaluation of grid are illustrated in contrast to traditional systems.