Solid phase microextraction (SPME) is a novel sample preparation method. It is fast, more efficient, simple and easy to operate automatically compared with the conventional solvent extraction methods. This paper describes the structure, principle, sampling method of solid phase microextraction. Especially the optimum extraction parameters include fiber, extracting time, extracting temperature, salt extraction, etc. Solid phase microextraction has been used in environmental analysis, drug analysis and food flavor analysis etc.