Sample preparation is a very important step in analyzing target compounds from a Complex matrix. An ideal sample preparation technique should be solvent-free, simple, inexpensive, rapid, efficient, selective, and convenient. Solid-phase microextraction (SPME) integrates sampling, extraction, concentration, and sample introduction into a single step. This method has many advantages such as short extraction time, high sensitivity, and high reproducibility. Extraction principles, experimental parameters, and applications of SPME for environmental analysis, food analysis, and drug analysis are presented.