The noise generated in the rotary compressor can be classified by pressure pulsation of the refrigerant and structural vibration. This paper deals with the noise generated by pressure pulsation of refrigerant in a rotary compressor. During the operation of the compressor, the refrigerant and the internal structure of the compressor have strong interaction with each other. At this time, the oil around the reed valve causes the compressor to overpressure the refrigerant, which is the main cause of noise generation. Therefore, the interaction between the refrigerant and the valve during the compressor operation is analyzed using the FSI technique. The pressure pulsation of the refrigerant and the behavior of the valve were analyzed. Also, the noise characteristics were confirmed through the spectrum analysis of the generated noise.