Vitual Machine (VM) technology encapsulates shared computing resources into secure, stable, isolated and customizable private computing environments. While serviceoriented computing becomes more and more a norm of computing, VM becomes a must-have common structure. However, creating and customizing a VM system on different hardware/software environments to meet versatile demands is a state-of-the-art task, especially for casual users working in new computing environments. In addition, VM configuration without system support is tedious, time consuming, and error prone. In this study, we propose a Virtual Machine Configuration System (V-MCS) for tackling this issue. V-MCS takes a systematic approach to enhance the flexibility and usability of VM. It provides an easy-to-use web interface to users to create their preferred configurations, and to convert the configurations into PAN documents for human-computer interaction and XML documents for machine automation. The underlying definition component parses the configurations and the spawn component generates customized VMs on the fly. V-MCS maintains and deploys these two-level documents when users login in the future. With the help of V-MCS, users can generate their customized VMs easily and swiftly. V-MCS has been implemented and tested. Experimental results match the design goal well.