Abstract: The simplest model in statistics,the observation of normal distribution of population is analysed in this paper，by using  the theory of observation  process.Though the problem has been solved，some new conclusions are given in this paper.According to the viewpoint of observation process，it is important not to concern with estimating value，but with the knowledge distribution about observed object，or posterior probability distribution，which is used to make decision.But in the process of making decision，there may be some process equivalent to estimation.This point is used to do analysis，and thus some conclusion which is not found before is drawn to give a foundation to further analysis.

Key words: observation process, statistics, information theory