Based on the basic theory of infrared radiation, a multi-band spatial azimuth optimization algorithm is proposed in this paper, in order to avoid the influence of the surface emissivity of the object on the infrared measurement. Through multi-band design and mathematical transformation derivation, an infrared multi-band temperature measurement vector group is constructed, enabling the closed-form solution of temperature under the condition of unknown surface emissivity of the measured object. Relevant experiments demonstrate that the calculated temperatures obtained using the multi-band algorithm exhibit a higher degree of agreement with the actual temperatures compared to conventional single-band infrared measurement methods, more effectively approaching the true values with smaller relative errors. The method can obtain the surface temperature of the measured object without the surface emissivity and the space azimuth calibration; reduce the error caused by space position in the infrared measurement process. The accuracy of infrared temperature measurement is guaranteed by the multi-band spatial azimuth optimization algorithm.