Signal lighting protection circuit

This invention discloses a signal lightning protection circuit including a third transient suppression diode crossing over a first and a second signal line, a second transient suppression diode connecting between the first signal line and the signal earth and a first signal line and the signal earth and a first transient suppression diode between the second signal line and the signal earth, a lightning device which is a first discharge tube connected between the signal earth and the protection earth. The circuit includes a first capacitor connecting between the first signal line and protection earth and a second capacitor connecting the second signal line and the protection earth.