Abstract: With the rapid development of photoacoustic imaging, it is increasingly used in aspects of biomedical imaging and diagnosis. The existing photoacoustic imaging products are limited to further popularization and promotion because of the excitation light sources, which lead to complex structure, large volume and high cost. The limitations and requirements of light source in photoacoustic imaging were analyzed. The present situation, advantages and disadvantages of different types of photoacoustic sources, including Nd:YAG, optical parametric oscillator, semiconductor lasers and light-emitting diode were summarized. This work should be helpful to select appropriate light source for photoacoustic imaging technology research and photoacoustic imaging product development.