The surface meteorological observation data file (File A) is a text file, which contains raw observation data of a month, including four parts (station parameters, observation data, quality control and additional information). The observation data consist of 20 surface elements with each having different record formats according to the type of the station and observation method. Because of its multiplicity and complicacy, the data file is inconvenient to use directly. A transformation system of surface meteorological observation data files based on VBA and the detailed procedures of data transformation is developed. It can be used to import File A into Excel in bulk for the data observed at different times and with different methods so to improve working efficiency.