The optical precision calibration constrains the ground testing performance of the double conical infrared horizontal scanning sensor. A real-time three-dimensional coordinate measurement system is established by using two electronic theodolites, and optical precision alignment of the double conical infrared horizontal scanning Earth Simulator is achieved based on above-mentioned system. Actual measured data are compared with the reference theoretical design value, and measuring loft and comparison are carried out repeatedly. Furthermore, the hot and cold boundaries of the Earth simulator are adjusted. These steps can constrain the accuracy of boundary feature point coordinates of the Earth Simulator within error of 0.2 mm. High-precision position control ensures the noise-equivalent-angle precision testing performance of the double conical infrared horizontal scanning sensor, and controls the noise-equivalent-angle (3σ) within 0.07 degree.