Abstract: The high-power plasma electric propulsion has the advantages of high specific impulse,large thrust and high speed increment.It will have broad application prospects in orbit control for large spacecraft,deep space exploration,interplanetary navigation and other space missions in the future.The magnetic nozzle is an important device on the plasma thruster.The energy conversion and separation of the plasma are carried out in it.The separation mechanism of plasma is a research hotspot of magnetic nozzles.This paper reviews the research status of magnetic nozzle,introduce the plasma detachment mechanism in a magnetic nozzle and its experimental research,also analyzes the influencing factors and conditional parameters of various detachment mechanisms,which provides some reference for the simulation and design of magnetic nozzle.