EMB (Electro-Mechanical Brake) which converts electrical motor power to brake clamping force at each wheel is a system that has been investigated and developed by various automotive part suppliers through the years. In particular, as the number of electrically powered vehicles, such as hybrid electric vehicles, electric vehicles and fuel cell electric vehicles, has expanded, the EMB has received increased interest due to its fast response that is much suited for effective cooperative control with regenerative braking. However, issues such as cost competitiveness, reliability and regulations need to be solved for commercialization [1-2].A new concept, the hybrid Electro-Mechanical Brake (hEMB) is characterized by a dual piston structure linked by hydraulics inside of the caliper. It is possible to reduce the required motor power and increase the level of emergency back-up braking through the amplification effect of the dual piston mechanism . The hEMB is composed of the caliper, dual pistons, spindle, gear actuator and motor. Here, the gear actuator acts to increase the torque generated by the motor. Although the motor is the source of oscillation, the actuator noise caused by gear friction but during this process has a more significant role in determining the overall operation noise of the hEMB system.This paper describes an experimental investigation of the effects of design parameters on operation noise of the hEMB actuator. A prototype hEMB actuator was built and the Design of Experiment (DOE) procedure was used to obtain optimal parameters for noise reduction. The effectiveness of the optimal parameters was verified through test results.