According to Beer’s principle, the distribution of heat radiation of an object to the surrounding space is cosine to its radiation direction. Consequently, obvious differences among the received infrared radiation is ubiquitous and even results in the error of infrared radiation temperature measurement, owing to the relative position relationship between the measured target and detector. To address the issue, the relation of target position to the angle coefficient of detector is firstly characterized quantitatively. A modified model of the amount of infrared radiation is subsequently proposed. Through the modified model, a quantitative compensation scheme for the amount of detector radiation is implemented from target radiation. Moreover, to test the reliability of the proposed method, an experimental measurement to derive the amount of radiation from uniform light is carried out by using the infrared detector. The results show that as the relative angle between the detector and uniform light increases, the gray values from the measurement of detector to uniform light under different θ-angles remarkably decreases. The relative error is lower than 0.04 after the quantitative compensation for the measurement of detector. The proposed method does improve the accuracy of infrared radiation temperature measurement and enhance the stability of test technology. It can provide a guidance for the error correction of infrared radiation temperature measurement.