Aiming at the problem that the triaxial geomagnetic attitude measurement model can not directly figure out the complete attitude information of rotating missile or the current attitude calculation by limit ratio and integral ratio method needs calibration curves and look-up table method, after establishing missile-borne geomagnetic attitude measurement model and missile-borne infrared attitude measurement model respectively, a biaxial infrared and geomagnetic composite attitude measurement method is proposed. By the biaxial infrared attitude measurement model, the pitch angle and roll angle can be directly calculated. Combined with the biaxial geomagnetic attitude measurement model, the heading angle can be worked out finally. Through error transfer theory analysis, the direct calculation of pitch angle and roll angle is realized by alternating solution to reduce the measurement error. According to the analysis of the experimental data, the feasibility of the biaxial infrared and geomagnetic attitude measurement method is verified. And the direct calculation errors of pitch angle, roll angle and heading angle are respectively within ±0.8°, ±0.5° and ±1°. The biaxial infrared and geomagnetic attitude measurement method is simple and effective, which can meet the attitude measurement requirements of rotating projectile.