The indication system of the present invention includes an indication device and an activation device. The activation device includes a cover and an activator movable with the cover relatively. Wherein a first sensor is assembled inside the cover to generate a first signal by sensing a horizontal displacement of the activator, a second sensor is assembled inside the cover to generate a second signal by sensing a vertical displacement of the activator, and then a transmission unit transmits the first signal and the second signal to the indication device; the activator is constructed with a combination portion and a control portion separately on two opposite sides. When the control portion is driven by a user to move horizontally or vertically, the combination portion can drive an operation member to be displaced synchronously. The indicator light of the bike is activated synchronously in conjunction with the indication system of present invention.