Precision Mechanical Design is a professional basic course for students majored in measuring and controlling technology. Combined the practical content of engineering application, this paper discusses the needs in the development of precision machinery design courses. The exploratory research and application of the teaching method of mechanical knowledge extensions are carried out in the major of measuring and controlling technology. In this paper, our students conduct extensive training on mechanical knowledge from the extended teaching knowledge in classroom to drawing homework after class. Through teachers' knowledge guidance and the sharing of mechanical design results, students can have a deeper understanding of the principles and structures of machinery. Students' design desire is aroused. After years of exploration in the extended teaching, students' application ability of mechanical knowledge in practice has been improved. This paper puts forward reasonable and useful ideas for the development of engineering education.