With the rapid development of infrared detection technologies, the study of the infrared characteristics of ground-object background becomes more and more important militarily. An empirical model of the apparent temperature field of ground-object background is set up according to the heat balance equation and the expression of apparent temperature associated with four basic meteorological parameters is derived. On this basis, the unknown parameter bi (1-5) is fitted for the measured data by the least square method. By comparison, it is found that the simulated result agrees with the measured result substantially. The error is controlled within 3.5. The simulated result reflects the tide of apparent temperature well. The method can give good estimation of the apparent temperature of ground-object rapidly. Through error analysis, it is found that the measurement accuracy of ambient temperature has the most evident influence on the calculation accuracy of background temperature.