Abstract: Stern- Gerlach experiment plays a decisive role in the modern physics experiment. As far as the experimental method is concerned,the molecular beam method created by this experiment has influenced many important physical experiments. As far as the basic principle of quantum mechanics is concerned,it is an example of quantum state preparation and a successful example of some quantum measurement. Based on a large number of related literature research and the combination of physical principles and historical materials,we hope to restore the true historical facts of Stern- Gerlach experiment. The focus is on clarifying the relationship between the experiment and the orbital angular momentum space quantization and electron spin.

Key words: Stern-Gerlach experiment, orbital angular momentum space quantization, electron spin