The invention relates to a noise reduction control method of a multi-split machine. The method comprises the following steps: (S1) when the multi-split machine is started by heating, an air pipe pressure Pc and a liquid pipe pressure Pliq are obtained, and meanwhile, the supercooling degree of each started indoor unit is obtained; (S2) a difference value of the air pipe pressure Pc and the liquidpipe pressure Pliq is compared with a preset reference pressure Py; and meanwhile, the obtained supercooling degree of each started indoor unit is compared with a preset reference temperature T1; and(S3) the openness of all outdoor electronic expansion valves of the outdoor units and the openness of indoor electronic expansion valves of each started indoor unit are adjusted according to the comparison result. The invention further relates to the multi-split machine, which adopts the noise reduction control method. The method has the following advantages: when the multi-split machine is operated by heating, the noise generated at the time of stopping the indoor units receiving stop instructions is effectively reduced, so that the user use comfort can be greatly improved.