The excessive noise of a hand-held blower-vacuum can be reduced with certain modifications. Spectrum analysis confirms the source of the noise as the measured acoustic pressure signal, performance characteristic and physical construction of the hand-held blower-vacuum. The noise is composed of electromotor noise, impeller noise and windage noise in the duct. Based on these sources, three approaches are applied in order to reduce the electromotor noise. First, the motor bearing is changed, and the brush pressure regulation system and brush immersion oil are improved. Second, the five-piece impeller is changed to a seven-piece impeller, and the edges of every piece are modified to 30 ofillet. Third, the outlet and inlet structures of the flow passage are modified to reduce the windage noise. Finally, a noise test of the sound power level is implemented. The test results indicate that the noise value is reduced about 22 dB under the normal working state of the hand-held blower-vacuum, thus fulfilling the noise limit requirement.