A circuit capable of providing stable timing clock includes: a step-down clamping circuit, an oscillating circuit, and a voltage potential-conversing circuit. The step-down clamping circuit that step down the input first voltage potential, and clamp to output second voltage, the oscillating circuit is coupled to the clamping circuit and is an oscillating circuit that takes the second voltage as a operating voltage to generate a first timing clock signal, which has a lower voltage potential. The voltage potential-conversing circuit is coupled to the oscillating circuit to convert the first timing clock signal into a second timing clock signal, which has a higher voltage potential. And it is a stable timing clock signal available for other system circuit.