A triangle wave generator with function of spreading frequency spectrum is provided. The triangle wave generator includes a switch control circuit, a current generator, an integrator, and a spread spectrum control circuit. The switch control circuit provides an internal clock and a switch control signal. The current generator is coupled to the switch control circuit and provides charge current according to the switch control signal. The integrator is coupled to the current generator and provides a triangle wave signal. The spread spectrum control circuit is coupled to the switch control circuit and the current generator for providing a current control signal according to the internal clock.