Virtual reference service has become an important issue since internet and E-resources for reference tools are now profound developed. Nowadays, most libraries provide asynchronous online reference service while only few libraries support virtual reference service with the functions of chatting, co-browsing and or video-conferencing, etc. To prepare for a virtual reference service program, library is suggested to investigate the need of patrons of the community, equip and organize sufficient digital reference resources, train and prepare for the knowledge and skills for virtual reference librarians, choose the proper virtual reference systems, issue a virtual reference service guideline for the library patrons as well as for the librarians, and, finally design proper evaluation indicator for virtual reference service.