The invention relates to a field measurement method for the acoustical power of an UHV transformer. The method comprises the following steps: respectively calculating a first acoustical power and a second acoustical power, wherein the first acoustical power is generated by a transformer blower and the second acoustical power is generated by the surface vibration of a transformer; superposing the first acoustical power and the second acoustical power, and obtaining the total acoustical power of the transformer. The influence of the measurement environment on the estimation of the acoustical power can be reduced. The problem that the acoustical power is difficult to test in the installation environment of the UHV transformer is solved.