Photoacoustic imaging (PAI) has been widely used in the fields of cardiovascular and cerebrovascular research, cancer diagnostic, brain science, and early diagnosis to diseases owing to its distinguished characteristics, such as noninvasion, high resolution, and high contrast. With the recent progress in opto-electro-mechanical technology, the miniaturized PAI technology has developed rapidly. This study focusses on the miniaturization of PAI system and provides a review for the development of PAI from the viewpoint of hand-held, wearable, portable, and endoscopic PAI devices.