In this paper, a liquid optical switch is proposed, and the 1550 nm infrared/visible switching function based on hydraulic control can be realized. An infrared light switch cavity, a visible light cavity and a liquid control cavity are stacked to form the main framework of the device. The glycerol, dyed liquid, and transparent liquid are filled in the cavities, respectively. Two elastic films are fabricated between the cavities for controlling the liquid volume of the cavities. With such a structure, in the initial state, the 1550 nm infrared light and visible light are absorbed by the glycerol and dyed liquid, respectively. The device shows infrared light-off and visible light-off states. When the elastic film is actuated by the liquid pressure, the shape of the elastic film can be changed. Once the elastic film touches to the substrate, a light channel can be formed so that the infrared light or visible light can pass through it. It shows infrared light-on or visible light-on states. In this way, the device can be worked as an infrared light and visible light switchable optical switch. The experiments show that the device can obtain the optical attenuation from ∼1.02 dB to ∼18.24 dB for 1550 nm infrared light optical switch and ∼0.66 dB to ∼8.70 dB @ λ=450 nm; ∼0.62 dB to ∼8.74 dB @ λ=532 nm; ∼0.77 dB to ∼9.00 dB @ λ=633 nm for visible light optical switch. The device has potential applications in the fields of optical fiber communications, variable optical attenuators, and light shutters.