Abstract: With the development of transformers towards ultra-high voltage, large capacity and intelligence, existing monitoring methods can not accurately capture the potential faults in the running state of the transformer. Based on the principle of a fiber Bragg grating sensor, a thermometer and an oil level gauge for multi parameter monitoring of an intelligent transformer are proposed. The thermometer and the oil level gauge are designed, the characteristics of the designed sensor are analyzed through experiment, and the test data are fitted by the least squares method. The results show that there is a good linear relationship between transformer temperature and thermometer wavelength. The temperature sensitivity is 10.275 pm/C and the fitting degree is 0.997 65. At the same time, there is also a good linear relationship between the oil level of the transformer and the wavelength of the oil level gauge. The sensitivity of pressurization and depressurization are 4.538 nm/MPa and 4.638 nm/MPa respectively, and their fitting values are 0.999 56 and 0.999 27 respectively. These values can meet the monitoring requirements of the multi parameters of an intelligent transformer.