The effect of the gas flow direction on the dynamic characteristic of a kind of the airborne total temperature sensor is discussed.Discovering that the deviation angle of the gas flow has an great effect on the dynmic characteristic of the sensor,the concept of directional sensitivity of the total temperature sensor is advanced for the first time.The reason of that is analyzed in this paper.And it is pointed out that,during the procasses of design,manufactrue and using,controlling the directional diviation is necessary,if not,the dynamic characteristic of the sensor will be aggravated.This conclusion can be adapted to other total temperature sensors with similar constructure.