Simulate the real application scenario of the helmet-mounted sight system (HMS) to carry out the calibration and positioning inspection of infrared visual positioning system, and quantitatively analyze the influence of infrared point source centroid extraction accuracy on helmet positioning. The positioning error inspection results show that, at the object distance of 500 mm, the position measurement accuracy of sub-pixel-level image coordinates can reach sub-millimeter-level, and the angle measurement accuracy can reach minute-level. Compared with the pixel-level measurement accuracy, the sub-pixel-level measurement accuracy in the X, Y, and Z directions has an improvement of 0.15 mm, 0.05 mm, and 0.02 mm. In the projection angles of φ, ω and κ, the sub-pixel-level measurement accuracy is improved by 0.05°, 0.22° and 0.22° compared with the pixel-level measurement accuracy. The positioning inspection provides a reference for the measures to improve positioning accuracy.