Runtime environment of software are becoming more and more dynamic and changeful, while pervasive computing and web services further this situation. Software systems are not only becoming larger, more complex, and also more rigid, which make it difficult to evolve software. This paper focuses on online evolution, more exactly, how to make online evolution process convenient and smart, with help of Runtime Software Architecture (RSA). Following issues are discussed in this paper: types of software environment changes, the incarnation of RSA, retrieval and manipulation of RSA, the relation between RSA and the runtime system, and a visual tool to show RSA, and make evolution process more easy and intuitionist.