As the home appliances are systemized, they have complicatedly assembled structure. It is reasonable to see the noise problem of home appliance in the viewpoint of system like vehicle and ship. There are various system analysis methods to resolve the noise problem [1-3]. To use system analysis methods, the system information like modal and path properties must be gathered and analyzed. But it takes many times to find out the system properties, so the simpler system analysis methods are needed. The coherence analysis method is useful as the system analysis method, since the method can identify the system property like the relationship between inputs and outputs directly and simply. In the paper, the partial coherence analysis is used for identification of the MISO system of washing machine, in which multi-input signals are vibration signals of motor bracket and an output signal is noise signal of washing machine. The relationship between the noise of washing machine and the vibration of the motor bracket in working status was identified and the parts of bracket closely correlated with noise were also proved by the relationship. And the noise of washing machine was controlled by redesigning the parts of bracket associated with the noise of washing machine based on the coherence function in octave band.