An over-current protection circuit for preventing a function module from over-current, the function module obtains power from a power source via an input port. The over-current protection circuit includes a path switch, a current detection circuit, a conductor switch, a first control module, and a second control module. The current detection circuit and the path switch form a loop with the input port and the function module. The current detection circuit detects a value of a current of the loop, and produces a first control signal when detecting the current of the loop is equal to or greater than a predetermined current value. The first control module turns off the conductor switch when receiving the first control signal. The second control module turns off the path switch when the conductor switch is turned off, thereby cutting off the loop.