To optimize the ’kalakala’ noise that produced by the plug hybrid electric vehicle when accelerating with a small throttle while in the charging state. A LMS device was used to acquire the noise of the driver's outer ear . Through filtering and playback analysis, it was confirmed that the noise is mainly contains the frequency bands of 250-350Hz, 350-500Hz, and 500-700Hz. The three frequency bands of the noise were used as carriers for Hilbert transform, and their envelopes were obtained for Fourier transform analysis. It was found that the modulation order of the noise is 0.5 times that of the engine ignition order, and the modulation frequency is 20-30Hz, which let the customer hears like roughness. Regarding the spectral characteristics of this noise, firstly, at the excitation source, the impact of reducing engine combustion excitation on this noise is explored. At the same time, selected a reasonable moment of inertia and frequency of the pulley torsional damper, to decrease the torsional excitation of the engine. Secondly, investigated the structural propagation path of the noise systemically, and effectively reduces the propagation path of the noise by increasing the dynamic stiffness of the powertrain suspension’s passive bracket and tuning a reasonable front driveshaft damper. Finally, based on the universal characteristics of the engine and the pressure rise rate map, as well as the goals of overall vehicle economy and power, different calibration strategies were attempted, and a calibration strategy that balances the three attributes was selected. Through the above measures, the three resonance bands of acceleration roughness sound were reduced by 3dB (A), 3dB (A), and 5dB (A), respectively. After optimization, the noise inside the car is almost inaudible.