In this work, we propose an enhanced design method for filterless class-D audio amplifier based on multilevel architecture. The multilevel technique consists of a multilevel converter and a time division adder followed by modulator. In this method, the modulated signal is arranged into several time divisions and then be integrated into a binary numeric. After that, the binary numeric is encoded to be a set of parallel control signal for multilevel converter. The multilevel converter will deliver multilevel signal to loudspeaker instead of conventional two-level signals. Consequently, improve the total-harmonic-distortion (THD) and signal-noise-ratio (SNR) significantly without sacrificing power efficiency. Moreover, we can apply the proposed method to many class-D amplifier designs simply insert a time division adder behind modulator and replace output stage with multilevel converter.