Abstract: The MTU series magnetotelluric sounders produced by Phoenix Geophysics Ltd. in Canada have been widely used in various fields of earth exploration because of their advantages, such as small weight and stable and reliable data acquisition. However, their special data formats make the data processing troublesome. At present, most of the data processing depends on the SSMT-2000 software developed by Phoenix Geophysics, which is not conducive to the improvement and application of data processing methods. By studying the formats of data files of MTU series magnetotelluric sounders, this study used the UltraEdit software to analyze the structure and rules of the data files and analyzed and studied TBL, CLB, CLC, and TS files based on the C# programming language. As a result, this study transcoded the data files from indigestible binary files into plain files that are easy to understand and provided the modification and editing module of TBL parameter files, the data analysis module of CLC and CLB files, and the transformation module of TS files. The data measured in the field were edited using the program developed in this study. The test results verify that the program can modify TBL file parameters, analyze CLB and CLC files, and convert TS files. Therefore, this study provides a new idea and method for studying such binary files.