The invention discloses a fiber grating sensor for temperature measurement of a lithium battery pack and a temperature measurement method thereof. The fiber grating sensor comprises an optical fiber,one or more fiber gratings are arranged on the optical fiber, and a packaging mechanism is arranged outside the fiber gratings; the packaging mechanism is provided with a hole matched with the shape of a lithium battery pole. During temperature measurement, the fiber grating provided with the packaging mechanism is installed on the pole column of each single lithium battery, and each fiber gratingmonitors the temperature of the corresponding single lithium battery; the fiber is connected to a fiber grating demodulator to measure the reflection central wavelength of each fiber grating; according to the relationship between the reflection center wavelength and the temperature, the temperature value of the corresponding single lithium battery can be obtained through calculation, the sensor can be conveniently installed on the pole column of each single battery of the lithium battery pack, temperature monitoring of each single battery is achieved, and as the optical fiber is an optical passive device, the sensor is high in anti-interference capacity and high in reliability.