Aiming at the problem that the precision of temperature measurement of infrared thermography（IRT） is greatly affected by the measuring distance. In order to improve the precision of pig ’s body temperature measurement

the influence of measuring distance on IRT temperature measurement and the correction method are quantitatively studied. In the animal experiment

the IRT ear base temperature is measured at different measuring distances from 1 to 4 m. The results of ANOVA analysis show that the ear base temperature（T） is significantly affected by the measuring distance（x）

and it is negatively correlated（r =-0. 923 6

p < 0. 01）. Then the linear

polynomial and support vector machine（SVM） algorithms are used to establish the relationship between T and x.After comparison

it is concluded that the optimal model is T = 0. 042 x2-0. 84 x + 39. 03. Therefore

the correction formula for the ear base temperature is as T’= T + 0. 84 x-0. 042 x2. After the variance analysis

the corrected ear base temperature T’ has eliminated the influence of distance（r = 0. 01

p = 0. 90） and indicating that the calibration method can eliminate the influence of measuring distance and improve the precision of IRT temperature measurement.