Extrinsic fabry-perot interferometric（EFPI） optical fiber ultrasonic sensor has high sensitivity and is not affected by electromagnetic interference. This paper applies it to partial discharge（PD） localization in oil. First a 2×2 EFPI ultrasonic sensor array is designed

which can be placed in the oil to detect PD ultrasonic signal. Then according to the steered response power（SRP） sound source localization theory to locate PD. Finally SRP and MUSIC（multiple signal classification） algorithms are used to process the experimental signals and compared. The results show that the EFPI sensor array can detect the partial discharge signal with high SNR in the oil. The SRP algorithm has less error than the MUSIC algorithm and can locate PD according to a single measurement

but the positioning accuracy should be further improved. The method proposed in this paper has reference significance for the practical application of EFPI optical fiber ultrasonic sensor in partial discharge positioning of electrical equipment.