PURPOSE: An adjustable window tinting system is provided to limit the amount of light and heat passing through a window by injecting liquid entering between two panes of glass. CONSTITUTION: The adjustable window tinting system comprises the steps of: one or more of storage vessel(1a, 1b, 1c) containing liquid with an effective concentration and color; an on/off control valve(5a, 5b, 5c) linked to the vessel through a tube(2, 2a); a pump, enabling on/off and rotation in a clockwise and counterclockwise direction, linked to the control valve through a tube; at least two glasses forming space, wherein one or more of air hole(7a) and an inlet(7b) on their upper and lower side, respectively; a micom(8) for controlling rotation of pump and on/off of control valve; filling level sensors for detecting filling or discharge of the space between glasses; a key input part(11) including an operation button corresponding to each storage vessel and a cancel button for stopping window tinting. The key-input part is operated by opening the control valve, rotating the pump in a clockwise direction, filling the space between two panes of glass with liquid under pressure of pump, and stopping operation of the pump and closing the control valve when the space is filled with liquid.