Optofluidics is the integration of optics and microfluidics(so-called lab on the chip). Wherein the actuation of liquid is a key technic. In a variety of methods for controlling microscale liquid, the light actuation is particularly interesting. The light actuation offers a novel way to control the flow of fluids for biomedical and biotechnological applications, etc.. The complexity and cost of devices sometimes may be greatly reduced by using complete optical control and may be more flexible in operation than other methods. However the light actuation of liquid is a burgeoning field as well as optofluidics. There is lots of work to do. Here we systematically describe four mechanisms for the light actuation of liquid based on the following points: optoelectrowetting, photothermal effect, radiation pressure, photosensitive substance. Optofluidics is the integration of optics and microfluidics (so-called lab on the chip. Wherein the actuation of liquid is a key technic. In a variety of methods for controlling microscale liquid, the light actuation is quite interesting. novel way to control the flow of fluids for biomedical and biotechnological applications, etc .. The complexity and cost of devices may may greatly reduced by using complete optical control and may be more flexible in operation than other methods. However, the light actuation of liquid There is lots of work to do. There we lots of work to do. Here we systematically describe four mechanisms for the light actuation of liquid based on the following points: optoelectrowetting, photothermal effect, radiation pressure, photosensitive substance.