Abstract: There are deviations between the Gaussian energy distribution model and the actual distribution of the star spots. In order to solve this problem, the rationality of the Gaussian energy distribution model with the simulation verification is reasoned in this paper. Gaussianbottomcutting energy distribution model is established aiming at the denoising in star tracker preprocessing，and then Gaussiantipbottomcutting is established according to the actual saturation in sampling. And the effect of the two models on the precision of the star centroid extraction are examined and compared accordingly through the simulation analysis. This can provide reference for improving the precision of the star spot centroid extraction.

Key words: star tracker, star spot centroid, Gaussian distribution, denoising