Body temperature of 35.4 ℃ is an abnormal phenomenon, the specific cause of the disease should be clarified and targeted treatment. Generally speaking, the normal axillary temperature of adults is 36℃-37℃, and 35.4℃ belongs to the state of hypothermia. Possible reasons are as follows: 1, measurement time is less than 5 minutes, measurement method is not correct, such as armpits are not clamped, thermometer mercury head or electronic probe is not placed in the armpits and so on, 2, the environment is at a lower temperature, wearing less clothes, such as warmth measures are not in place. 3, endocrine factors, such as hypothyroidism, usually accompanied by a pale yellow face, puffy eyelids, lethargy, slow reaction and other symptoms. 4, inflammation and infection. 4, inflammatory infections, such as severe pneumonia, etc., in the high fever before the emergence of chills, this time the measurement of body temperature may also appear hypothermia. 5, taking too much fever-reducing drugs or did not reach 38.5 ℃ above the taking of fever-reducing drugs, this time to immediately stop the drug, drink the right amount of hot water, to the hands and feet to do the massage, hot compresses, etc.. Excluding external factors, long time body temperature is low, it is recommended to endocrinology for routine blood, thyroid function test, identify the cause of the disease after symptomatic treatment.