The Modern Library ubiquitous computer hardware and absolute lack of relative surplus situation, as well as the construction of electronic resources and the absolute lack of relative surplus problem, which makes the today's hottest VMware virtualization technology is applied to the "cloud" Library Construction on, break the current library is expected to become the best solution to two problems above, the paper not only analyzes the necessity and urgency, also talked about the use of VMware virtualization technology to build cloud library.