MRTD is an important technical parameter for evaluating infrared imaging equipment,which is directly related to field action distance of the equipment,and often used to predict the field action distance.The operating temperature of general military equipment is from -40℃(or even lower)to +55℃(depending on the application scenario),and within this temperature range,changes in MRTD are caused by changes in target radiation energy,detector noise,optical transmission,etc.The general equipment is only tested at the factory for room temperature MRTD,and no MRTD is given for other ambient temperatures.In order to solve the above problem,the influence of ambient temperature on the signal transfer function,noise,modulation transfer function and other factors of imaging devices is considered in this paper,the variation law of MRTD under different ambient temperatures is explored,and the relationship of MRTD under different ambient temperatures is established.MRTD under other ambient temperatures through room temperature MRTD prediction are obtained,thus the prediction accuracy of field action distance under different ambient temperatures is improved.