The thematic map is one of the most intuitionistic forms for presenting the research results in geophysical exploration. Nevertheless, a final result map needs to be revised and improved many times. According to the characteristics and requirements of geological interpretation map and with a section map of interpretation by electromagnetic method as an example, the authors designed and compiled an automatic drawing program by using Python language and its rich third-party libraries. In this paper, main links, such as drawing unconformity line (wave line), deleting micro-short line, polygonization and color filling are described in detail. Meanwhile, the key code are provided.