Class-D amplifiers are widely used in automotive audio systems because of their high efficiency. In modern car sound systems, multiple amplifiers are used to provide good audio effect. However, typical class-D amplifiers have a high idle-power, which can drain the battery quickly. To solve this problem, an ultra-low idle power class-D amplifier is proposed in this thesis. The simulation results show that this amplifier can achieve very low idle power while maintaining competitive linearity and efficiency.