In this paper, the methods of data processing and drawing for borehole three-component magnetic measurement are discussed. The data processing formulae of tilted well for the axial system magnetometer were inferred. Based on Object-Oriented Programming (OOP) and using VB2005 as the program language, the authors successfully designed and implemented a data processing and drawing system for borehole three-component magnetic measurement. In order to test the system, this paper has described an example of borehole three-component magnetic measurement, which proves that the system can effectively process the data and accurately draw such graphs as graph and vectorgraph. As a data processing and drawing system for borehole three-component magnetic measurement, this system is perfect and has a wide application vista.