Abstract: Protein kinases are intimately involved in the pathogenesis of many diseases such as cancer, inflammation, and autoimmune and neurological diseases. Therefore, kinases have been widely studied as drug targets over the past three decades. As of April, 2020, the FDA had approved 59 small molecule kinase inhibitors (SMKIs) in the emerging field of targeted drug therapy. This paper focuses on the biochemistry and pharmacology of these 59 SMKIs and 121 SMKIs for which structures can be retrieved and that are now in phase Ⅱ and Ⅲ clinical trials. In addition, this paper also conducts a simple analysis of several popular targets and their inhibitors.