An experimental investigation has been made on the flux characteristic of internalmixing atomizer with compressed air and transformer oil as working media.The experimental formulae correlating the flow coefficients of oil and gas with the operational and structural parameters of internalmixing atomizer are acquired.According to the experiments,there exists great dispersion for the flow coefficients in different internal atomizers or in the same one with different operation parameters,and the maximum deviation may reach 100 percent comparing with some recommended design calculation ranges.The results indicate there is great difference between the experimental correlative formulae of the two cases when the oil pressure is greater than air pressure and its reverse case.