Infrared temperature measurement technology is widely used in the detection of surface temperature distribution of hot stamping parts. However, the accurate infrared temperature measurement for complex parts is still a problem due to the deviation of emissivity. In this study, a novel directional emissivity calibration was proposed for 22MnB5 hot stamping steel. A mathematical model considering directional emissivity was established and verified. Based on the projection and interpolation method, the directional emissivity is assigned to each pixel in the thermograph shot by infrared thermal imager. Finally, a high measurement precision within ± 25 °C was achieved for temperature measurement on 22MnB5 hot stamping parts.