Fearful emotion is a response to the external stimuli of human. The generation of fearful emotion could lead to the change in the facial skin temperature. According to the principle of infrared thermal images reflecting the temperature distribution on the surface of objects, a method based on infrared thermal images is proposed to recognize the fearful emotion. Firstly, a heat transfer model is simplified by curving fitting of exponential function, and the facial infrared thermal image is converted into the blood perfusion pseudocolor image to find the regions of interest (forehead region). Then, features of the blood perfusion change curves are extracted (slope, confidence coefficient, mean value, and standard deviation), and the correlation between the features and the selfassessment score of the fearful emotion is analyzed using Spearman correlation coefficient. Finally, the standard deviation which is highly related to the selfassessment score is applied to recognize the fearful emotion of the subject. The experimental results show that there is an obvious decrease in the blood perfusion of forehead region in the presence of fearful emotion, which is consistent with observations of previous studies, and the standard deviation (with a threshold of 0.14) of the blood perfusion values is a main feature for recognition of the fearful emotion. The proposed method is demonstrated to be satisfactory and reliable with an accuracy of 85.7% for all the 28 tested subjects.