Abstract: The plasma diagnosis of the ion thruster discharge chamber is of great significance to study the plasma characteristics in the discharge chamber and the performance of the discharge chamber.In order to study the plasma diagnosis technology in the discharge chamber of ion thruster，development status abroad was investigated.The working principle，application scope，implementation points，technology maturity and diagnostic reliability of contact electrostatic probe technology and non-contact spectrum technology were analyzed.Electrostatic probe technology is mature，the theory is perfect，the cost is low and the operation is easy，but it will interfere with the plasma.Spectrum technology can significantly reduce the interference of the diagnostic tool to the plasma，obtain more precise plasma parameters，and is increasingly used in the field of plasma diagnosis.The research and analysis can provide a reference for the domestic plasma diagnosis technology of ion thruster discharge chamber.