Providing services in a wireless environment with existing wired-based GIS solutions have many limitations such as slow communication, processing rates, and screen size. Among the components, data is considered to be the most important factor in GIS. In this paper, I describe MVF, the most recent technology pioneered by GIS researchers. MVF is a format for efficient usage of spatial object in order to express, save and transform in mobile GIS. First, I describe the definition of MVF syntax, then the implementation of Header Section Generation Module and Main Section Generation Module through the API. Since the issues of network traffic and Hangul processing in mobile GIS are important, I especially consider development of MVF in terms of spatial data size.