Whispering gallery mode (WGM) resonators with high optical quality factor (Q) are highly sensitive to environment changes and are used in various sensing applications. We have developed a high-precision temperature sensor using a compactly packaged lithium niobate (LN) WGM resonator. This sensor offers a sensitivity of 34.38pm/℃ and a high resolution of up to 5.6×10-4 ℃. It is portable with high Q, making it suitable for using outside the laboratory. The device is also resilient to changes in humidity, enhancing its practicality.