Abstract: Static angle calibration devices are applied to detect the static angle measuring accuracy of large scale photoelectric theodolites, and the stabilization accuracy of angle datum which is affected by the optical axis orientation of autocollimator is required less than 2 (rms) in 24 hours. According to the requirement, the impact of ambient temperature on angle datum was studied. Experiment results proved that the optical axis orientation of Cassegrain reflective collimator used in the static angle calibration devices was not influenced when the ambient temperature changed in a certain range, but the static angle calibration devices no longer met the precision requirement when the environmental temperature was beyond the range of specified operation temperature. In order to ensure the measurement accuracy, specific requirements of laboratory infrastructure were put forward. In addition, the calculation results of optical design software showed that the inhomogeneity of the collimator manufacturing material, assembly tolerance, stress were the main factors affecting the optical axis orientation.