Fiber optic ultrasonic sensors based on Fabry-Perot (F-P) interference can have their probes embedded within transformers, offering advantages in sensitivity and anti-interference capability. However, the internal environment of transformers is complex, and factors such as temperature, pressure, and electric fields may affect the performance of fiber optic F-P sensing probes, altering their operational characteristics. Therefore, this paper investigates the influence characteristics of the transformer internal environment on fiber optic F-P ultrasonic sensors. The effects of temperature and liquid pressure on the fiber optic F-P probe were studied through experiments, and the distribution of the externally applied electric field within the fiber optic F-P probe was analyzed through simulations. It was found that the impact of temperature on the fiber optic F-P probe is significant and should be a primary focus, while the effect of liquid pressure on the cavity length of the fiber optic F-P probe is minimal. The electric field distortion increases within the F-P interference cavity, suggesting that the fiber optic F-P probe should be placed at the transformer edge in low field strength areas, and propose an edge computing-based suppression strategy for temperature interference. This study aids in the design and application of embedded fiber optic F-P probes.