During the radiation therapy of the laryngeal tumor, the laryngeal motion occurred from swallowing can cause the tumor to move away from the radiation area and lead to a decline in treatment efficiency. Therefore, to detect the time of swallowing of a laryngeal cancer patient is essential for later remedial measures. However, since metal occlusion cannot be contained in front of the irradiation rays, many conventional detection methods cannot be used. This paper presents a Fiber Bragg Grating (FBG) based method for swallowing detection. The FBG sensor is attached to the thyroid cartilage of the human throat. The movement of the thyroid cartilage during the bending causes the FBG sensor to bend, causing the wavelength of the reflected light of the sensor to change. The change of the wavelength of the reflected light reflects the movement of the thyroid cartilage. In the experiment of healthy adults, both the camera and the FBG sensor were used to detect the movement of the throat during swallowing. The results of the camera detection were compared with the results of the sensor detection. The result illustrates that the FBG sensor can correctly count swallows and efficiently detect the swallowing movement time.