An ultra-sensitive temperature sensor with enhanced Vernier effect based on Fabry-Perot interferometer (FPI) and Sagnac interferometer (SI) cascade was proposed and verified through experiments. FPI was made of the thermal sensitive material polydimethylsiloxane. SI was prepared using the panda polarization maintaining fiber. The temperature sensitivity of FPI is positive, while the temperature sensitivity of SI was negative. Therefore, when they were cascaded with similar free spectral ranges, the enhanced Vernier effect was produced, which can further improve the sensitivity magnification factor of traditional Vernier effects. The experimental results showed that the temperature sensitivity of the enhanced Vernier effect sensor was as high as −93.97 nm/°C, which is the highest sensitivity reported in the literature. The temperature sensitivity of traditional Vernier effect sensor is −42.26 nm/°C, and the sensitivity of enhanced Vernier effect sensor has been further improved by 2.22 times. When manufacturing enhanced Vernier effect sensor, there is no need to desensitize the reference interferometer, only the sensitivity symbols of the two interferometers are opposite, so it will not increase the manufacturing cost and difficulty of the sensor. In addition, the sensor has good repeatability and stability.